Exactly. Go with one of these. You can get them much cheaper on TigerDirect.com. Also, the building of the PC should be what you are MOST worried about. If you connect things wrong, mount the motherboard incorrectly, don't make the correct cable connections, or any other relatively small errors very bad things can happen! That would be aweful to buy all this expensive stuff and then have it ruined because of building errors.
Vista Home Premium 64bit
XP Pro SP2 64bit
EDIT: I guess newegg must have lowered its prices recently! I hadn't noticed the lower prices there now!
-Get the Vista Home Premium OEM for $99