Tim
Not sure if you know this but virtual memory is actually hard disk space and used to be called a swap file. In windows, there is an option to manually allocate virtual memory space or to allow Windows to manage it for you.
You can check these settings from the control panel by clicking system>advanced>settings>advanced.
Assuming that the swap file is managed by Windows which is the default and dynamically sizes the swap file size, I would suggets that you have insufficient space on the C drive (swap file usually at C:\).
You can delete temporary files from C:\documents and settings\
your name\local settings\temp and empty the windows explorer cache from within IE (Tools>internet options> delete files)
Also, you might find some stuff in C:\Windows\Temp , these can be deleted.
Empty the recycle bin.
Have you got loads of stuff stored on the desktop? This is actually part of the C:\ drive too and maybe these things could be stored on another drive?
You can also move the swap file to another drive with more space on it in control panel>system
Roger, so Mac OX does not use virtual memory? Must have a lot of RAM in there then