To summarise;
Dual CPU, 1.4ghz each.
1gb RAM.
256 MB Video Card.
I use 1 GB RAM, although you can do a lot better.
Your computer is sort of low to middle end. Its not going to do Crysis and backflips, or Crysis at all, but its enough to run games from, perhaps, pre 2008, and a number of rather satisfying ones.
I'd upgrade the video, as all decent cards don't do shared memory, and I suspect that you don't have a Video Card at all, hence the lack of dedicated memory. Given an Intel chipset, its probably a delightful (T_T) Intel Integrated Video, which isn't going to be doing much for you, so definitely get some dedicated video memory in there. This will speed up games considerably. Last time I tried that video solution, even Halo was chugging badly, so a Video Card is a good idea if you're planning to stick with the machine.
RAM sticks are cheap and easy, so see about buying another few GB's if you have the cash.