An older system I have has a single-core Athlon 64 with roughly similar performance to that model. It can run older games, but by "older" we're mostly talking about games from around 10+ years ago, at least when it comes to titles that were moderately demanding for their time. Games like Quake 3 Arena and UT2K4 would likely run rather well on that hardware, at least as long as you are not trying to push high resolutions. If you have a couple gigabytes of system RAM, titles like Left 4 Dead 2 would likely be playable at 720p as well, so long as you don't mind occasional performance dips when there are a lot of enemies on-screen. For things like 2D indie titles, you could even run a lot of newer stuff, as those games tend to be less demanding.
That system of mine has a graphics card that's about twice as fast as that one, but it tends to be limited more by CPU performance. Do you own any of this hardware already, or are you looking to buy or upgrade it? It's probably not worth spending too much on hardware that old.