general pc advice, for minecraft if you have trouble loading new areas or constant low fps it's really one of three things
- archaic graphics system
and i mean really quite bad, any GTX 2xx+ or HD 4xxx+ series card should work for minecraft ( anything in the last 6 years, really )
- slow/old/overburdened cpu
turn some background apps off, check your performance monitor ( ctrl+alt+del > task manager tab > performance tab for win 7 ) then while running your game / application if it's constantly 90+ then you need more power. also check your ram isn't full, if it is get another stick 4gb is usually the max for a 32 bit system, but you can have as much as you want on a 64 bit, go nuts.
- slow harddrive
if file transfers are below about 60mb/s most things will preform terribly, including the horribly optimised mine-craft world generation system there's a nice app here: http://www.techpowerup.com/downloads/1749/atto-disk-benchmark-v2-46/
which will give you the speed of your disk(s) use the internet to find out if that's normal for your drive.
if all else fails hire your local computer geek, ask for advice.
( free food usually works )
the glorious pc master race is here to help.