Looking at a gaming PC.

[WyldRage]

Don't skimp on the graphics card: it's the single most important piece of hardware. You have to learn what the numbers mean in the card.

For ATI ex. 5870, 5 is the generation, 8 is the power, 7 is linked to the memory used IIRC.
For nVidia ex. GT285: 2 is the gen. 8 is the power, 5 indicated an improvement I think.

So, a 5470 is very weak, while a 4870, though last gen, will be much more powerful.