Will be used mostly for Gaming. Already have case (Antec P180) with Antec Neo 550HE Power Supply (pls comment on this if it is not enough power). I will be re-using hard-drives for storage as well as re-using optical drives (all SATA).
Intention is to build a good gaming rig for now, with as much future upgrade posibility as possible within budget. I don't plan on Cross-Fire now, hence the single Nvidia card. Any and all help is appreciated!!
Almost identical to what I plan on upgrading to next week. Without starting another whole debate I'd recommend starting with Vista64. With or w/o SP1 beta your hardware is plenty enough that gaming will be identical between Vista and XP for all practical purposes. Plus you'll get your full 4GB of Ram.
I built the system under my name on the left 3 weeks ago, its very similar to your proposed one. I would get more PSU and vista 64. If you like blue neon my case and keyboard look great together. Good Luck