How much RAM does windows vista ultimate use with no programs open?

compared to windows xp pro how much ram does vista ultimate use

How much RAM does windows vista ultimate use with no programs open?microsoft updates

In my conservative estimation about a half a gig.

How much RAM does windows vista ultimate use with no programs open?windows server 2003 internet explorer

My system has 2 gigs, and it used 550 megs. Vista reserves a certain amount even if its not using it, so it looks like it's being used.
If you have a 512MB RAM, then its going to take about 40-60 percent of your memory.
bout 600mb (with all aero enabled)
This can be dependent upon how many programs you have running in the background and what options are enabled in Vista. You can generally count on about 350-500 MB of ram being used if it's available to the system. Keep in mind that Windows uses more virtual memory than system memory depending on how much RAM is available to it at the time.