Ok, so I got YODM3d yesterday, it's a program wich lets you use several desktops at once, by making a "cube", wich you can rotate to switch to other desktops. So, I'm thinking, if I get a WM program, I can swiftly switch between OS'es. Pretty cool idea, eh? But I don't know if it'll work. Now to the main question:

Is WMware player free (not trialware) and can it emulate everything I need? Does it support my current system (Ie. Is it incompatible with anything?) and is it the best option for me?
/ Thank you in advance, RrR (Ken)

This feature is standard fit in Ubuntu (linux) ;)

VMware viewer is indeed free, but I'm not really to sure what you have in mind as you're a little light on detail.

I simply want to be able to emulate an OS as a program in WinXP. Did that clarify it?

And does Ubuntu really have OS- switching/emulating as standard? :O

It has the multiple desktops and runs virtual machine really well.

This system allows you to use different flavors of Internet Explorer -- IE 5.5 - IE 6 - IE 7

Thinstall Application Virtualization2

Supposes you could throw Linux in the mix