My last girlfriend and I more or less broke up because of it. Had a fight over not having much to talk about, or me accidentally leaving msn signed in when I started gaming. Quite frankly she loved the nice guy side of me, but was ashamed of the gamer side. (she's a car loving, horse riding country girl)
I have dated a gamer before, was pretty cool....but things just didn't work out. I must say, being geeky in some way, shape or form is the highest thing on my list of things a girl must have, though a girl who accepts and isn't ashamed of my gaming/anime and sometimes fakes interest is fine too. (like how we watch chick flicks =p)