Thank you folks!
My first WPMU installation is up and running with the domain mapping plugin after just a few hours.
I didn't have any experience with VPS/dedicated server/CPanel that's why I was a bit reluctant of installing WPMU on a VPS.
I finally decided of using a VPS after reading many threads on VPS vs shared hosting and domain mapping plug-in.
A special thanks to Andrea for the ebook, it helpeded a lot since I didn't have experience with CPanel.
Demetrio