It sounds to me like you need an updated driver, but neither nVidia nor Dell has supported your GPU in quite some time.
You could try a driver from http://www.laptopvideo2go.com/drivers?dev=&sub=&whql=0&lang=0&orderby=version&dir=desc&os=&os%5B%5D=xp, but there's no guarantee that it'll work for you. Sorry, you might be SoL.
Anyway, I've been using Steam since Half-Life 2 was released on at least 5-7 different machines with varying levels of internet connectivity and I've never had a problem with a game that was caused by Steam.
Actually, I take that back...I had a CTD issue with Fallout 3 that I solved by turning off the in-game Steam GUI. That's the only one I've ever had...and I have something like 130 games on Steam due to their diabolical sales.
