Your board sounds different to mine, at least in colour. I have 4 black ports which are the true onboard ones (positioned nearest the inner edge of the board), which I managed to get 3 drives max to run from (adding a 4th resulted in no boot no matter which was where), and 3 blue ones and a red that are the marvel ones at the bottom. Unfortunately I don't use the blue or red ones as I have no need, just adds about 5 seconds to boot time and I don't want that
It's also possible the bios is playing with the boot order of the drives, as the true onboard ones will probably take priority. Never used raid on this board to know what it's listed as, but whatever it may be make sure the added drives are at the bottom of the drive list and windows should resist the urge to rename all your partitions, and will hopefully boot.
As for the graphics card a 8800gtx is definitely not the best card, it doesn't do any of the video decoding for hd, so assuming this box has a good cpu (I'd hope so if you game with a gtx on it!) you'd just as well run any card that can handle the res required and has a dvi port. Like a 7300gt... (lowest priced card that doesn't steal system RAM, at least it was when I got one

) If you wan't hd content to play though you'll need to look into hdcp, I believe there is a software bypass but it hasn't been of interest to me yet.
Good luck with the drives
