Here's some resource you might find useful :

http://support.microsoft.com/default...;en-us;q308356
http://www.microsoft.com/technet/tre...t1/dsgch08.asp
http://download.precise.com/pub/whit...ser-Quotas.pdf

And here's a commercial application for you:
http://www.oneapp.co.uk/site/product...al_control.cfm

Also, I found out (from link 1) that the process Lsass.exe is the one that steals all your memory. It's a "feature" that MS feels increases the effieciency of your system.

Cheers,
cgkanchi