I tried VirtualBox a few years ago. But I didnt have a need for it so I removed it to free up hard drive space.
If you want a virtual environment that is Windows XP, if you can locate PC Anywhere 2007, you can use that and run a virtual XP system along side your already existing Windows XP system. On the occasion that I need to run 2 or more isolated environments on the same Windows based computer, I use Virtual PC 2007 and its as simple as linking my VHD for Windows XP and I can then have my virtual computer running along side my physical. For my virtual environment its XP Pro SP2 with 384MB of System RAM allocated to the virtual system. So multiples of virtual environments is only limited by amount of RAM, CPU processing power to juggle multiple systems physical + virtual system(s), hard drive space, and Windows Licenses to be legal with 1 license per virtual environment.
Occasionally i will fire up my Virtual PC 2007 which runs on my Windows 7 system and use that to test software without making a mess of my main computer. If its a game that I am testing that woudnt test well in a virtual environment, I then use my test rig that I have a system image of that after I test a game, I can wipe it clean by clean image placed onto the drive and then its clean and ready for the next test. This systems name is crashtestdummy
The background image on crashtestdummy is this
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