Zorin is definitely one of the easiest Linux distros to use, IMHO. Most of the things ship pre-installed and pre-tweaked to make life easy for a new Linux convert. Further, it looks quite similar to Windows 7 and it really helps.
From Zorin OS 8 http://mylinuxexplore.blogspot.in
Zorin has a commercial and a non-commercial line of release. For this review, I downloaded the free Zorin OS 8