Welcome to NeoSmart Technologies, Alejo.
The answer: It would indeed have been possible - but for one problem: you upgraded from XP to Vista.
I believe you're referring to this guide: http://neosmart.net/blog/archives/188
The only thing you can do at this point isOriginally Posted by So you Overwrote your XP?
1) Return to the upgraded Vista which still has your programs, accounts, and settings; but has the bugs too.
2) Keep on with this build and grab the files you need from the Windows.old directory.
In the future, check out NeoSmart's latest Vista guide before upgrading to Vista: 10 Steps to Vista Upgrade Success