a virtual memory question

[WhiteHawk]

I know virtual memory is used by the CPU as RAM but, how
fast of ram is it?  Do I only want virtual memory if I run out
of Regular RAM or vid memory?
  If SDRAM is 100 or 133
and  DDRAm is 266 or 333
what is virtual memory???

[Innominate]

Virtual memory is also known as swap space.  When the system needs ram, it takes programs in memory which aren't doing anything, and writes the ram they use onto the hard drive, freeing up real ram for currently running programs.

Compared to ram, virtual memory is disgustingly slow, programs simply don't run from the disk, they need to be reloaded into ram before they can run again.