[Ham-Computers] Reinstalling XP PRO

[WØQFC]

I need some help!
Some time ago, I installed XP PRO on my machine and have just learned from 
MS that it is not a legal copy of the software.
I had bought it from a person that I thought could be trusted and the CD 
looked like a original, but was fake. (LONG story)
I know about MS's program that lets you send back the fake CD, etc., etc., 
but I do not want to send it to them because they want me to tell them  from 
whom I got the CD.
So, the big question is: How to I install a legal copy of XP PRO on my 
machine without loosing all the stuff I already have installed?
Would it be possible to do this by doing a complete backup of the system, 
re-formatting, install the new software and then do a restore?
Would this procedure copy any of the "Illegal" stuff back to the machine?
I would appreciate any help the group might have.

TIA es 73

Gene, WØQFC
Spring Hill, Florida
WEB SITE:
http://www.w0qfc.com