I have a scanner which has 32 bit drivers only (Microtek Scanmaker 6000), so that pretty much confines me to 32 bit, though some people reckon they've hacked 64 bit drivers by mixing models. So, as I understand it: If I go OEM, that means choosing 32 or 64 bit from the get go, while if I go retail, I can change? Next question, Home premium or Professional. Is XP mode needed only for some specific things, or for a lot of XP era software? Is there a compatibility setting to run older stuff without using XP mode as such?