Office 2007 pro plus change registration number

I have purchased a new MS Office 2007 Pro Plus software and want to change the registration on my computer.  I currently have the same software on my home computer from my old work place but would like to remove their number and put my new one in.  Would prefer not to have to reinstall and reset everything up the way I like it.
Had a link that told how to do it but my registery doesn't seem to match their instructions.
Here is the link:  
http://news.office-watch.com/t/n.aspx?a=1445&z=27
I have this month to get my license in so I can claim the free 2010 version of Office free.
Thanks, Pat