Vista + Office 2007 in 4Mb
Windows Vista Ultimate (compare prices) is an edition of Windows Vista that combines all the features available in the other Vista editions. It's the most expensive edition, but it combines the mobility and business functions of Vista Business with the entertainment features of Vista Home Premium.

It's probably the best windows XP for play games... and propably you are asking, why?
Let me u explain :




• Windows Extreme Gaming only use about 37MB of Ram Memory (30MB If u terminate explorer process before play a game), after the second start when It completes all the changes. Worshippy

• Are updated to the last SP3, fixes an usefull updates. Worshippy
• Already have a SATA Drivers Pack that is loaded before the windows install process, so u can forget all the problems with ur SATA HDD. Worshippy
• The OS size is about 200MB, only. And 100MB of applications. There are availeables from the Booster menu.
• Is still necessary activate the Windows Installer MSI Service before install a games. Start -> Administrative Tools -> Services -> Windows Installer -> Start. (Right click, properties, automatic. If u don't want repeat all the steps again).