When I try to start MP PTW, I get low virtual memory errors, then get booted out of game. My VM cache is set at about 756 . What do I need to set it to?

Pentium 4 2.2 Inspiron 8500
512 MB DDR
64 MB DDR 4X AGP NV28 3D Video
30GB hard drive
Windows XPSP1 Home
Dell Truemobile 1300 WLAN