TobiSGD is correct that you normally do not have anything to worry about. As a rule, have a backup and know how to use it.
I can't say what the issue is with two installs, do you mean they both asked you the same question and warning?
Virtualbox ought to install correctly. Microsoft offers a similar virtual machine app for xp that might be used. I have used it too for a very long time without issues. Virtualbox and VMplayer may be the two common ones for first time use.
Last edited by jefro; 08-27-2012 at 02:52 PM.