System cleaning and Parallels partition

I was wondering if running system cleaning (such as clearing caches and all the other functions under Onyx) will affect files and preferences inside Windows XP (which I have under Parallels). Thank you!

The Parallels environment is contained within a file, so your XP world just looks like a file to OSX.

If you want to do the usual housekeeping on your XP environment (cleaning caches, etc) you'll need to do it from within your Parallels environment.