(I'm lazy, I admit it, but it's been a long day, so I will just copy and paste something I wrote in this thread some time ago)
I hope I don't sound as some biased fanboy (which I am, by the way ), but Spider-Man can hurt Iron Man. He can web him up very fast and throw him a few times against a building. Or under a passing train. Or use him a few minutes as a punching bag.
Iron Man will feel that, trust me.
Spider-Man can beat Iron Man, but I admit he would have to give everything he got. But then again, I also believe Iron Man is not fast enough to hurt/damage/hit Spider-Man.
And below is something I found on the Internet (thanks to the writer):
For instance, one comic had an Iron Man from the future go back in time to get a retina scan from a child who would grow up to be a psychopathic murderer. He accidentally injures the kid in the process and Spidey goes absolutely ape-shit. By the time Spidey's finished, there are pieces of that suit hanging off! The face-plate was cracked, the breastplate was smashed, and the guy inside was actually bleeding from his wounds!
Moral of the story : do not underestimate a berserk Spider-Man. Iron Man is tougher and stronger, sure, but not half as fast as Spider-Man. Spider-Man can dodge (reflexes ! agility !! spider-sense !!!) every attack of Iron Man while knitting a sweater for MJ.