[MLD-Grounds-Keeper-Willie]

Sam did not have the ring for so long so it could not really 'corrupt' Sam. At that point, Sam's loyalty to Frodo was greater than the desire of the ring. I don't have my book w/me so sorry if I'm wrong about this part, but I don't think Sam ever put on the ring, he only held it. And I'm sorry if I'm wrong once again, but I think that Sma had a brief struggle with the ring, but Sam resisted it. So Sam had it for too little a time to really want it back, or in that case, to not give it back.

As for the whole Gollum/Bilbo question, the reason might have to do with how long they had the ring for. Gollum had it for a really long tome, so his age might take longer to catch up with him. Whereas Bilbo didn't have it for as long, so age might have crept up quicker.

And maybe age creeps up to those that willingly give up the ring. For them, they are 'over' it. Bilbo gave it up, so he gave up all the benefits of having it as well, i.e. prolonged life. But gollum lost it, he did not choose to give it up. I think that a part of the ring still lingered in gollum. it kept age from creeping up on him while it kept the desire. And although Bilbo did give it up, it was like a drug and the ring can be tempting, so he still wanted it, but he did not seek it, like gollum.

Hope that helps.