There's a saying that alot of us in the guitar community use to describe the process of buying cheap pieces of crap guitars and throw ing new parts in them to try to MAKE them into good guitars:
You can't polish a turd!!
A part of me is thinking that this phrase applies in your situation.
Honestly, for the amount of money you'll spend fixing it up, then getting good arrows, then a new sight, then a new rest, etc. your still stuck with an old crappy bow. You'll have no guarantee that this bow will even tune properly for you!
You could buy a brand new bow "package" for just a little bit more money. I know one of our local pro shops sells "ready to hunt" bow packages. Absolutely everything you need to shoot...bow, arrows, sight, rest, quiver, etc from Martin and Hoyt. Both are excellent bows. As I'm typing this, I have a Bass Pro Shop catalog that lists complete bow (sans arrows) setups. The cheapest runs around $129 and the most expensive is $499.
My advice is to go ahead and go to a local pro shop, see how much they would charge to fix up the old bow
BUT compare that to the packages the pro shop is most likely selling, I think you'll find that going new will be the better value.
-Mike