check that link I gave you. That was a link to a 512mb stick of RAM I believe, but it was PC3200 RAM so you'll need to check what kind of RAM your laptop can handle not just the amount because we already know 1gb is your max. Check out either newegg.com or zipzoomfly.com the prices are pretty close to each other, don't let zipzoomfly's free 2nd day trick you though, it's all marketing techniques, newegg marks their prices down lower, but have shipping whereas zipzoomfly has higher prices but free 2nd day AIR which doesn't mean it'll be there in 2 days that would be UPS 2nd Day....not 2nd day air...but yeah either of those sites will give you a good selection of RAM.
As for helping you choose the appropriate stick and whatnot, we'd need more info about your comp. Good luck