I'm not as tech savvy as most on here, but I do know that in the world of video cards $50 won't buy much. I design homes with CAD software and the video card I purchased (GTX580) was around $500 at the time (the price has since dropped). My guess is that those who viewed this thread probably thought that your budget was too low. After all the research I did looking for the best card, anything below about $250-$300 was a crap shoot.
is a benchmark site I found pretty useful to at least compare the speed of each card. Your best bet is probably networking with other gamers to get their input. But again, most of the serious gamers will spend in access of $300 to get the performance to run their games.
One thing you need to consider; some video cards will require you to bump up your power source. Check the manufacturer specs online and make sure you know what you have. An upgraded power source will cost at least another $50 (or more for a decent one).
Sorry I didn't respond sooner, I figured one of these brainiac guys would have chimed in by now