Jag googlade lite snabbt och hittade detta:
With SP1, Windows Vista will report the amount of system memory installed rather than report the amount of system memory available to the OS. Therefore 32-bit systems equipped with 4GB of RAM will report all 4BG in many places throughout the OS, such as the System Control Panel. However, this behavior is dependent on having a compatible BIOS, so not all users may notice this change.
och
At the end of the day, we don’t have much of anything bad to say about
SP1 outside of the “fix” for displaying the amount of installed memory on 32-bit systems, so our recommendation is that all Vista users to install SP1 once it becomes available to the public at large. It won’t knock most people’s socks off, but the file and network performance improvements are long overdue and will be noticeable for most users. Ultimately, any user who has felt slighted by the poor copy performance of Vista will find relief in SP1, as will anyone whose pet-issue has specifically been fixed in Vista SP1. Anyone else who didn’t like Vista for other reasons will be no more impressed by SP1 than they were by the original version; there are a few quirks that should have been resolved in SP1 that were not.
http://www.anandtech.com/systems/showdoc.aspx?i=3233&p=1
Edit: fortsatte läsa eftersom det var intressant och fick bekräftat det som stod i första citatet: skillnaden med SP1 installerat är endast att den visar hur mycket ram du har, men du kan fortfarande inte använda mer än 3.5...smart!