Ok, I am fixing to upgrade to Windows vista, but I really need to know certain things. 1. How many activations do you get. I am well known for switching systems like I switch my socks, so this is a huge factor to me, how many activations do you get with it? 2. What is the difference between OEM and Retail? Advantages of Retail? 3. What OS is required for the upgrade? 4. I can get them all pretty cheap, so what is the best one Home, Premium, Business or Ultimate. I am 1000% gamer, nothing else. 5. If I have DX10 installed, can I still play my DX9 games?