Sixaxis doesn't have rumble, but the Dual Shock 3 does.

No software update can make a controller without rumble parts in it rumble.

You should also note whether or not you have interest in HD movies. Do you have an HDTV and an interest in Blu-Ray or HD-DVD? That makes a difference, as well.

Really, you should just tell us what kind of games you're interested in, or simply look up the exclusives coming to both consoles in the next couple years.