After reading this vademecum DocWiKi I've done these simply 6 steps:

1) ftp my entire site from http://www.yyy.zzz/site to local hard disk

2) re-ftp local copy in http://www.yyy.zzz/site2

3) with phpmysqladmin 2,5,5 i'd backed up my db1

4) in db.sql I'd changed every link to http://www.yyy.zzz/site
to a link http://www.yyy.zzz/site2

5) create db2 and merged entire structure

tested my new site --> OK

6) then I've overwrited new XOOPS 2 (downloaded today!!) into new site

launched .. and Wrong!!!!!

It give me the forst page of setup, It doesn't recognize that there is an old site to migrate!!!!

helpppppppppp

:(((