We had a similar situation, but it was rather convert somebody, Birri Gomes, a Portuguese dude who goes to Karate needed a lift to the competition with us...Weeelll, he's into hip hop and 'bling', we tried a bit of Black Sabbath with Paranoid, I even tried Master's Apprentices by Opeth and other things, but it didn't work, so don't try those.
I think you should try:
Bob Marley:
Whatever song has a guitar in it, you need a good beat flowing through you, jolly stuff is good to play as well as the rest.
Symphony X:
Diving Wings of Tragedy - If you want some good symphonics, as your friend is a guitar player, well they can shred and are quite symphonic, its good for getting a taste of a good tune and a good shred, this song provides both, as well as rocked up versions of classical orchestral pieces and quire singing.
Dream Theater:
In the Name of God
Stratovarius:
Anything from Dreamspace - Similar reason to Symphony X
Jimi Hendrix or Stevie Ray Vaughan:
Any song or any Hendrix song - Two extremely talented guitarists who died before their time, Jimi was the reason why I got a guitar in the first place a great start
Trivium/Metallica/Slayer:
Well I suppose mainstream music is something everybody has to listen to
Opeth:
Good death metal, good melodic stuff and something, the two mix together, effing good band, one of my favourites, known as progressive death metal, its not all death metal but they're my biggest influence as far as playing something melodic or playing rhythm guitar.
"Listen to Jah Music..." - Bob Marley