depends on the specs of the PC and how many programs you are running.

do not tweak windows vista. its already full of tweaks .
you will end up with a slow pc and full of errors

umm the first person to answer this question is a spammer plz ignore

try to download tuneup utilities which has a great range of ways to speed up your machine by cleaning up unwanted stuff, defragmenting your drive to decrease loading times and tweaking to change settings (to make it more efficient eg. getting rid of the gadgets bar on the right of the screen) and prevent applications from all running at once when starting your computer

you forgo “looks” and effects for efficiency =]

hope i helped

1)Place a Windows XP setup disk in the CD ROM drive
2)Reboot
3)Install Windows XP, which runs immeasurably faster and more stably on any PC
4)Forget you ever heard of Vista, at least until it’s fit for general release (about 2014)