From what I have read, the Full Retail will install Vista 32-bit or 64-bit. The Upgrade will upgrade Windows XP or Windows 2000, and the OEM version is a Full 32-bit version or a full 64-bit version that when activated that License is then locked to your motherboard, meaning that if you ever...
MSI RX1900 Crossfire Edition $150 MIR ends 12/31
http://www.newegg.com/Product/Product.asp?Item=N82E16814127208
288.99 after rebate + $6.41 3 day shipping at newegg.com.
Valid at these stores:
ABS.com, ActBuy.com, Atacom.com, Ateck.com, Axiontech.com, Buy.com, BuyStarPC.com...
I just got my MSI $100 rebate on my X1900XT just a few days ago. I'm seriously considering this. Though I would have to buy a new case as mine won't hold another big honking vid card.
Edit:
I should look at the dates. There is a new on that goes till 12/31/06 for $150 off of a X1900XT CF...