as a living testimony, I strongly reccomend avoiding the use of virtual memory unless you're gonna use it once in a while, with long time spaces between uses (rendering a 3d scene of editing graphics or moving big amounts of data). you'll end up using phisical space that you might need for other purposes, and the amount of space you use won't be available until you format or defrag.
and if you're running BC from a slave or secondary IDE disk, don't even think about it.
if you know you have a fast HD, you can still use it, but don't rely on it too much.
if you need more memory, the best choice is to buy memory sticks, or reduce the graphic quality.
is your CPU dual-core?