Help regarding x86/x64 - Win/Mac

Hello everyone!

I have a 21.5 inch higher model Imac currently running WinXP pro x86 and all has been well for a while. Ive recently started getting into Adobe After effects CS4 and RAM usage is becoming an issue. I could really do with that extra RAM recognition.

XP currnely only recognizes 2.97GB of the 4GB. I hear there is currently no support for XP pro x64 but there is however support for Windows 7 x64 via Bootcamp. My main query here is now at idle my system is using around 350mb of RAM. After some searching i have found that Windows 7 seems to on average use around 1GB or RAM at idle.

Would it really be worth upgrading to x64 Win 7 to obtain full use of the 4GB when considering the extra RAM it will require to run? Bearing in mind the fact that now i will be able to run 64 bit After Effects which will probably increase performance. All in all as you can tell i would just like to get the best performance out of my machine as possible without using Mac OS.

Any help or advice would be greatly appreciated.