I will admit straight up, if money is no concern then Ultimate is going to deliver the best bang. It includes the superb computer backup tool, media center, Ultimate extras, business applications, better support for high-end hardware and additional special features. On the other end of the spectrum we have Vista Home Basic, which is designed for those who don't care about the Aero interface or other additions such as Media Center and random content creation tools.
Home Basic vs. Home Premium
No Aero interface, including transparency in many parts of the GUI
No Media Center
Five included Windows games, instead of nine
No automatic network backup
No relationship between PC and Xbox 360
No advanced slideshows
No Movie Maker / DVD Maker
Weak Tablet PC functionality
No SideShow Support
Home Premium vs. Ultimate
No advanced complete system backup tool
Small business apps, such as Fax and Scan
No Ultimate "extras", which could include games and special utilities
No BitLocker hard drive encryption software
No automatic "Shadow" copies of your documents
No Remote Desktop
No advanced group policy editor
Inability to run UNIX-based applications (through SUA)
No support for dual CPU's (2 physical processors) or 128GB of memory
Ultimate's Advantages
Ultimate "extras", which could include games and special utilities
BitLocker hard drive encryption software
Advanced complete system backup tool
Windows Media Center with Xbox 360 capabilities
Same business apps as included in the Business edition
Automatic "Shadow" copies of your documents
Remote Desktop
Advanced group policy editor
Ability to run UNIX-based applications (through SUA)
Support for dual CPU's or 128GB of memory
Encrypting File System (EFS) support
Support for resyncing files for getting work done while offline
The highlighted features may influence gaming capabilities. However, the Home editions are more VFM. As newer quad procs starts to show themselves, and faster RAM chips are invented, Ultimate will be likely to be preferred.
Actually this is a tricky question. :S Anything can't be said for sure until the DX10 thing becomes mainstream.
(Taken from a few sources). :ashamed: