assuming you are talking about running XP inside a Parallels VM it should work with whatever key/mouse hardware your mac mini is supporting. keep in mind there are some quirky problems with the key mapping / behaviour right now but it shouldn't affect you so much ( | and \ key, caps lock is a bit flaky)
The Apple bluetooth mouse and keyboard worked fine for me in the text portion of the Windows XP installer. Unfortunately I was not able to complete the install as I could not eject the CD to insert my Windows 2000 disk (the upgrade installer requires verification of a previous version of Windows), but I assume the keyboard and mouse would work fine once installation is complete. ..Al