You may encounter Windows Vista installation issues on systems being built with 4 GB or more RAM installed on the motherboard.
If installing the OS with a pair or more of 2 GB sticks of RAM, you may experience STOP errors.
Have a pair of 1 GB or even 512 MB sticks around for the install. Use that pair for the OS and post OS installation driver updates. When Vista has booted up into the installed and updated OS, shut down the system and swap out that pair for the 2 GB sticks.
Boot the system up, and Vista should recognize the 4 GB , 6 GB, or more RAM in the system.
Oh, and make sure your BIOS is the most recent before starting the install! Early board BIOS versions were also prone to killing Windows Vista installs.
Microsoft Small Business Specialists