Quick items to share/remind...
Set Minimum and Maximum to the same value between 2-3 times the available RAM on your PC. Making them the same means that Windows does not adjust the amount that is available on the fly.
Dedicated "drive" for Virtual Memory - If possible use a second drive and dedicate it to Virtual Memory, easier for a workstation.
Vista Users - USB memory stick can provide extra RAM via Vista Ready Boost feature. Thanks to Ed Tallmadge for making me aware of this feature though I have yet to take the time to install Vista myself since somewhere along the way I found that I really don't enjoy rebuilding my computers anymore?!?
One general comment on RAM - resist the urge to install a 64 bit OS and "under-power" it by only providing 4gb of RAM. You will likely get poorer performance. You need at least 6gb of RAM, ideally more like 8. I'm not "geeky" enough to explain why in technical terms adequately but the folks I trust on these matters assure me that we shouldn't do it.
Last, keep in mind...your hardware and software combinations are different from mine and others so your mileage will vary! 8-)