Opinions Requested: New PC Build

Hello, building a new PC for the first time in 8 years (yes, my current machine is THAT old). Looking for some opinions. The following lists what I plan to purchase. Is the list overkill, inadequate or just about right? Thanks.

Intel Core 2 Duo E8500
Gigabyte GA-X48-DS4
OCZ Reaper HPC 2x2GB 240-pin DDR2 SDRAM
Corsair TX750W 750W ATX 12V
(2) Radeon HD 4780 1GB (in Crossfire)
(2) Western Digital Caviar Black 1TB (in RAID)
Sound Blaster X-Fi Fatality
regular DVD-RW
Antec 900 Case + any fans i need for more cooling
Windows XP or Vista (not sure yet)

Uses: games, everyday use, DVD watching, may do a bit of overclocking (not really hardcore about it)

Concern is the PSU, would it be adequate if i were to add another hard drive or two in the future? At this stage, it's more unlikely, but just wondering. I was considering the HX1000 but that seems overkill to me and costs about $150 more.

Thanks for your responses.