This article:
http://technet.microsoft.com/en-us/library/bb490962.aspx
describes a little tool shipped with XP, 2003, and on up. But it doesn’t say how to execute it. Every time, in the above article, you see “pagefileconfig.vbs”, it should read:
%systemroot%\system32\pagefileconfig.vbs
With that one caveat, the tool can be very handy.