Hopefully this thread will provide a single source of advice about hardware choices for new builds and upgrades. There are several PC-knowledgeable Escapists, so chime in if you have any comments. If you have anything to add, or disagree with information in the OP, send me a message or post to the thread and I'll try to work it in if it's relevant.
If you're looking for advice, post a budget, the parts you want to hold over (if any) from your current machine, and the games you want to play or programs you want to run (include settings and resolution). The information in this post and the next is provided assuming that you'll use your PC primarily for gaming, so those who have other needs should take the info with a grain of salt.
And, of course, feel free to share your specs or any horror stories (or words of encouragement) you have.
Current contributors:
Oopsie [http://www.escapistmagazine.com/profiles/view/Horticulture]
Your PC needs the following components to function:
-Motherboard (Mainboard): Recent motherboards also contain network and sound chips, some include weak GPUs
-CPU (Processor)
-GPU (Video Card)
-RAM (Memory)
-Disk Drives (Hard Drive and Optical)
-Case
-PSU (Power Supply Unit)
And, of course, a mouse, keyboard, monitor, and speakers if you hope to interact with it.
Crash courses in each component type are under the spoiler tags in the next post.
For those seeking instant gratification, three builds follow at three different price points: Budget (~$500), Mid-Range (~$700), and High-End(~$2000). The mid-range build is all most gamers will need, and even the budget build will handle any game out today at reasonable settings. They're updated from time to time, and the high-end build assumes that you will overclock. It should be noted that none of these have wireless cards built in, so grab a wireless card [http://www.newegg.com/Product/Product.aspx?Item=N82E16833315041] if you'll be far from your router. The linked one is cheap and works well with XP, Vista, and Windows 7.
The Build: Budget* (~$530):
Updated 2/2010
CPU: Athlon II X3 440 (3GHz triple) [http://www.newegg.com/Product/Product.aspx?Item=N82E16819103843]
Motherboard: Gigabyte/AMD 770 [http://www.newegg.com/Product/Product.aspx?Item=N82E16813128419]
GPU: XFX Radeon 5770 (1 gig) [http://www.newegg.com/Product/Product.aspx?Item=N82E16814150462]
RAM: 4 gigs Kingston DDR3-1333 [http://www.newegg.com/Product/Product.aspx?Item=N82E16820134792]
PSU/Case: Antec 300+430W PSU [http://www.newegg.com/Product/Product.aspx?Item=N82E16811129065]
HDD: Seagate 500GB [http://www.newegg.com/Product/Product.aspx?Item=N82E16822148395]
DVD: LG SATA DVD-RW [http://www.newegg.com/Product/Product.aspx?Item=N82E16827136167]
What it does: Max out many games up to 1920x1200 and most up to 1680x1050. Run all current games on the cheap.
The Build: Mid-Range* (~$950):
CPU: Intel Core i5 750 (2.66 gHz Quad) [http://www.newegg.com/Product/Product.aspx?Item=N82E16819115215]
Motherboard: Gigabyte P55 [http://www.newegg.com/Product/Product.aspx?Item=N82E16813128425]
GPU: Powercolor Radeon 5850 [http://www.newegg.com/Product/Product.aspx?Item=N82E16814131184]
RAM: 4 gigs G.Skill DDR3-1600 [http://www.newegg.com/Product/Product.aspx?Item=N82E16820231277]
HDD: Samsung F3 1TB [http://www.newegg.com/Product/Product.aspx?Item=N82E16822152185]
DVD: LG SATA DVD-RW [http://www.newegg.com/Product/Product.aspx?Item=N82E16827136167]
PSU:OCZ 600W (Modular) [http://www.newegg.com/Product/Product.aspx?Item=N82E16817341017]
Case: Antec 300 'Illusion' [http://www.newegg.com/Product/Product.aspx?Item=N82E16811129066]
(Optional)CPU Cooler: Cooler Master Hyper 212 [http://www.newegg.com/Product/Product.aspx?Item=N82E16835103065]
What it does: Max out most games at common resolutions (1920x1200 or less), and perform well at higher resolutions with all titles. Compared to the budget build, it's an improvement in all areas, especially video/gaming performance.
The Build: High-End (~$2000)
CPU:Core i7 930 (2.8 Quad) [http://www.newegg.com/Product/Product.aspx?Item=N82E16819115225]
MoBo:Gigabyte X58(+SLI, USB3) [http://www.newegg.com/Product/Product.aspx?Item=N82E16813128423]
RAM:3x2 gigs G.Skill DDR3-1600 [http://www.newegg.com/Product/Product.aspx?Item=N82E16820231225]
GPU:2xXFX Radeon 5870 [http://www.newegg.com/Product/Product.aspx?Item=N82E16814150443]
SSD (OS+Apps): Intel X25-M 80GB (OEM) [http://www.newegg.com/Product/Product.aspx?Item=N82E16820167016]
HDD (Storage):Samsung 1TB [http://www.newegg.com/Product/Product.aspx?Item=N82E16822152185]
Blu-Ray:LG Blu-Ray Combo Drive [http://www.newegg.com/Product/Product.aspx?Item=N82E16827136162]
PSU:Corsair 850W [http://www.newegg.com/Product/Product.aspx?Item=N82E16817139009]
Case:Cooler Master HAF 932 [http://www.newegg.com/Product/Product.aspx?Item=N82E16811119160]
CPU Cooler (Optional, for heavy overclockers)

rolimatech Megahalem [http://www.sidewindercomputers.com/prmeforinso7.html] (Add a fan and thermal paste)
What it does: Max out everything; validate your existence. With two of the fastest available GPUs and a fast SSD, this is beyond overkill for most users. If you have two grand to burn, though, this is your machine.
*the budget build is now using a micro-ATX motherboard, which is smaller than standard ATX If you plan to use several PCI/PCI-e expansion cards, spend a few dollars extra for a standard ATX board with more room for expansion.
Want a way to take advantage of your swanky PC/PS3 while you aren't gaming?
Join the Escapist Folding@Home [http://folding.stanford.edu/] team!(
Folding@Escapist)
Team#: 171286
What is Folding @ Home?
Folding at Home is a distributed computing project for the simulation of protein synthesis.
What the hell does that mean?
It's for science!
Folding at Home takes advantage of the unused power of your computer (and thousands of others) for medically-applicable biological research. A group at Stanford, with grants and support from the National Institutes of Health and several major tech companies, set up a system to run complicated protein simulations on other people's computers to do computer-intensive medical research. This research may be applicable to the treatment of a number of diseases, including Mad Cow, Alzheimer's, and many cancers.
How do I get started?
It's easy. Go here [http://folding.stanford.edu/English/Download], select the appropriate client for your operating system, download, and install. Your computer will be folding proteins in less time than it takes to fall asleep in organic chemistry.
If you have a fancy-schmancy video card(GeForce 8xxx, 9xxx, or GT2xx, Radeon HD), it can help you fold even faster. You need to use a special (Windows-only) client, though. Get it here [http://folding.stanford.edu/English/DownloadWinOther].
PS3 owners can even get in on the fun. Point at least one of your 7 processors this way [http://folding.stanford.edu/English/Download] and grab the PS3 client from the bottom. Yeah, you don't get to play Halo, but 360 owners don't get to
cure cancer!
What's all this about a team?
The team bit is just a way to log folding work done by its members. It's totally optional, but lets us log the power Escapists have directed to a good cause.
It's easy to join. Just enter the Escapist team number
171286 at setup or in the "Configure" menu.