It allows you to run multiple virtual desktops and switch between them with user customizable hotkeys, there is also a full-screen preview selection (shown in the image below) or the ability to add a taskbar selector (in the bottom right of each of my virtual desktops below. Most windows have the ability to right click at the top and you will be able to access the Dexpot context menu to switch which VD you want the window to be attached to, or if you have the taskbar selector enabled you can drag and drop windows.
The only quirk that I don't enjoy is the fact that if I open songbird in VD1 and then accidentally in VD2, if I close the window in VD2 it will also close the window in VD1, this may be an issue that is specific to Songbird or it may apply to any program that only allows one window/instance. Future testing will answer this question.
If you wanna try Dexpot or some other VD Software check out one of the following links
XP/Win7 support
Dexpot
VirtuaWin
XP only
Microdesk
Virtual Dimension
Microsoft Virtual Desktop Manager
Note: some of these softwares support back to Windows 9x, for those of you with a box running a legacy OS