I found these really interesting. When I was really young, I heard about the Gospel of Barbabas. I coudn't say if it was fabricated or not. As for the Hindhu scriptures, supposedly they are thousands of years old and are not.
http://en.wikipedia.org/wiki/Gospel_of_Barnabas
http://www.irf.net/irf/comparativereligion/hinduism/muhammad.htm
To add to this, I heard in a lecture on video that Mohammed (SAW) is mentioned in the Torah as Mohamadim. In this instance the 'im' at the represents respect but also can be used generically as a plural.
You're free to read Tenach however you want of course, but for clarification the word used in Shir Hashirim is Machamadim, a plural derivation of Chamad, meaning desirable. The context is a love poem to Jerusalem and the Torah. (It is part of the Tenach but not the Torah.) The idea that it relates to Mohammed is a bit like suggesting that where it says "B'reishit bara elohim et hashamayim v'et haaretz" ("In the beginning God created heaven and earth"), Genesis actually refers to God creating Rabbi Shamai - idolatrous nonsense to a Bible believer.
[size=10]The whole problem with the world is that fools and fanatics are always so certain of themselves, but wiser people so full of doubts.[/size]
[size=9]Bertrand Russell (1872 - 1970)[/size]
'Cheeko mame tah kim, vechulo Mohamadim. Zeh doudi, Me zehre he, beyna Jeruzalem'
Songs of solomon 5:9-16
What does that mean?
He who sacrifices his conscience to ambition, burns a picture to obtain the ashes!