Suspicious noise when riding, any ideas?

UPDATE:

Just been playing around, including slackening off the chain, and the problem went away alot. Then I discovered the cause, a nasty tight spot in my chain! The tight chain has been exaggerating the effects of the tight spot.

Got to say, my chain is very oily, but maybe more gunky, noticed a few bits of red on it too, hence rust! So I could buy a new chain, and then new sprockets too don't I? OR.. remove it and brush it in parafin to clean it, then re-oil. I'm a bit of a novice, I was going to do the later first on Saturday.

My bike doesn't have a soft link in the chain I can find, so it looks like I'm gonna have to remove the wheel and what not. Anyone have any advice before the novice attempts to fix his chain with the help of Mr Haynes?

Thanks, Tom.