Ah, but you can always buy new core components later. The X800 Pro (well, I would suggest a 6800GT, but that's another story) would be a nice performance increase in the meantime.
Then again, there's the whole PCI-E debate as well (in which case I'd recommend an X800XL) and then you would need a new motherboard and CPU anyway.
ya i agree about the 6800GT if you are planing to upgrade later with another agp setup but not to pcie, i guess it depends on which way you want to swing