Time for a new machine

I’ve been out of Touch (no pun intended) and need a new machine.
Had another motherboard fail (old shuttles are finally crapping out on me)

Want to build around the new Nvidia 280 1G card.
Budget is $1500 which only leaves me with $1100 after the card purchase.

Seems XP Pro is still the recommended OS.
What about RAM speed, is 800 low latency still fine (4G)?
Figured on getting a fast duel core instead of quad core cpu.

Please chime in especially if your already running the latest gpu.
I’ve mentioned getting a laptop for over a year, but glad I waited cuz I really need another workstation now and will be happy to list my specs once I purchase.

Thanks,
~Shawn (head spinning on new egg)

Sending this thread over to Computer Hardware.

~Shawn