Not sure if you can run Halo 2 Vista? Read here.

[Mr Buckshot]

I'm just wondering what do you think would be better to get because there both the same price, So what's better a Radeon X1650 or a Radeon HD 2600?

The Radeon HD 2600, of course. It supports DirectX10 so it's better. In terms of DirectX 9 performance, though, the X1650 and HD 2600 are not too far apart.