I have a PS3 and a 360 (new premium with HDMI):
1) The 360 is CONSIDERABLY louder than the PS3, but only when it's playing games. That's not to say it's horrendous, but the PS3 is silent and the 360 is audible.
Playing DVDs etc the 360 is as quiet as the PS3.
2) PS3 includes a lot of things that are optional extras on the 360 - the PS3 comes with wifi, a web browser, integrated blu-ray player etc (at least the 60gb version does, I've not checked out the new 40gb version).
I was particularly pleased with the fact I plugged my Plantronics USB headset into the PS3 and I can use that for voice comms - you can't do that with the 360 - you have to use the crap mic that comes with it, or pay £30 for the wireless headset.
In terms of what the machine can actually do, the PS3 has more features than the 360 (although it doesn't mean games are better on it).
So far, I think PS3 has had a shaky start, but with games like Drake's Fortune out now and the 2008 line up of MGS4, Little Big Planet etc, I think the system will hit it's stride this year.
Ultimately, I think it comes down to which system exclusives you'll be more interested in because most games will be available on both systems (and hopefully, the PS3 versions will be equal to the 360 versions - quite a few haven't so far).
I also had my first 360 red ring on me, and no-one knows for sure if they've fixed the problem with the new Elites/Premiums yet - PS3 certainly doesn't have any hardware issues on that scale.
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