Hello Gazza33, I would have to agree with marc2003, the Nvidia 8800GTX is a better overall card than the Nvidia 9800 GTX and is also slightly cheaper.
I would also get the 64-bit version of Windows Vista Home Premium. As well as being able to address all 4GB of RAM that you are looking at purchasing, it is a faster, securer and a much more stable platform to be using.