That would be enough to play any of those. I play them all with a geforce 3 ti200 :S. Half life 2 runs best, out of the 3 I think half life 2 looks best when you have but minimum system requirements.
dang your gonna run it pretty slow... i don't even know if u can run it..... i'm too lazy to go look at specs but it's gonna be pretty bad because that is a very slow processor nowadays and you should have at least 512 ram but i'm suprised half life 2 runs BEST with your 64 mb card undead, i have a 2.2 athlon and 512 and a radeon 9600 pro 128 and with farcry it lags with medium settings
From the 3 games, I get the highest fps in Half life 2. I was surprised aswell. I was thinking that this would be the time to upgrade to a new videocard, I was wrong.
@dmacfour: videocard does make a big difference and yours is better than mine, however, your cpu and ram are a bit low so I dont know how it will do. My advise is wait for a demo (dont know if there's going to be any) or download the game and see if it works. If it does work, buy it.