I couldn't find the link on allmusic.com, so I did this on napster.com instead. I hope it's still good (I think that it should be)

Start with: Tally Hall
End With: Black Sabbath
Tally Hall -> Five For Fighting
Five For Fighting -> Goo Goo Dolls
Goo Goo Dolls -> Foo Fighters
Foo Fighters -> Queens of the Stone Age
Queens of the Stone Age -> Black Sabbath

From Tally Hall -> Black Sabbath can be done in only 5 links

(Also, I actually chose the bands beforehand, and this ended up working out! I didn't cheat and just choose a band that was listed, if you understand what I mean)