Some excellent suggestions on this ver issue of Virtual Memory running low.I have dealt with this issue many times before in my line of work and one thing I can suggest beyond these knoelegeable suggestions posted thus far is to be sure and run te defrag utility on XP.while not a direct solution to the immediate
problem,defragging the hard drive does "tidy up the house" on the hard drive
fo better overall performace as the hunt for program fragment on multiple volumes is reduced .In that vitual memory is borrowed memory from the hard drive,defragging will make this much slower virtual memory avaialable as needed
on a somewhat faster basis and makes the hard drive more efficient in servicing requests from multiple running programs.

Nonetheless.just keep in mnd that some programs,especilly graphics programs and game programs,can be real memory hogs and if it is needful to run several such programs at once,an upgrade of te existiing DRAM is probably the best option in the long run