I don't think the problem is that girls don't like geeky guys - in fact, I was disappointed with my most recent ex because he wasn't nerdy enough, and my current beau is probably one of the most nerdy people I know. I think the problem with geeks in general lies in a few areas:
A) You're too devoted to your particular area of geekdom, and you're not willing to cut back to make room for other things. There's nothing wrong with being a devoted gamer or musician or what have you, but it's all about balance and making the other person feel like you actually care. One of my good friends, a huge nerd, has had several girlfriends since I've known him. The reason why both of his relationships fell apart basically boiled down to an unwillingness to sacrifice game time and time with his friends to do things his girlfriend liked.
B) Simple lack of shared interest. This ex of mine, while he wasn't a ckmputer or game nerd, was a huuuuge Japan, literature, and film nerd. His idea of a great day would be browsing Japan on Google Earth for several hours, reading some poetry, then watching a really old, artsy Danish film or something. All these things, while I made an honest effort to participate in them and enjoy them, bored me to tears. Whatever it is you love most, I think it works out better if you find someone who shares that love.
C) You don't have to go out of your way to be popular or sexy, but chances are good that if you're really not trying, you're not going to get noticed by most girls in a positive way unless you're honest-to-god handsome. Harsh, yeah, but it's true. I was overjoyed when I finally got a boyfriend who actually had a sense of style and cared about the way he looked - it's really nice to see guys in something that'a not an old Black Sabbath T-shirt and an ill-fitting pair of jeans. Also, a good haircut and some facial hair maintenance goes a long way.
D) You'd be surprised at how many girls have overlapping interests. People just tend to assume that regular, attractive girls aren't closet nerds, when I've found through personal experience in meeting people that they're often much quirkier than you'd think. Don't be afraid to put yourself out there - after all, it's the only way you'll find someone who likes YOU.
E) More a personal pet peeve here than anything else. I like smart guys, but I hate arrogance. I've met a definite number of nerdy guys who consider themselves smart that fall under this, perhaps by accident. I myself was once an oblivious arrogant smart girl until someone pointed it out to me, and then I was mortified. Most of the nerds I've met are really quite nice and down-to-earth, but some of them kind of make you wary of the others.
Just a few thoughts. Hope something I said sheds some light.