Here is some information concerning memory usage at idle on this latest computer build.
Windows XP Pro(no service pack or updates) 82Mb
XP Pro(all service packs and updates) 365Mb
Windows 7(fully updated) 743Mb
As you can see, Xp started pretty lean and fast. Not so much in it’s latest form. Now uses 4 times the memory.
And, Windows 7 doubles that memory usage, at idle.
Good thing memory is cheaper today 
Ralph