i think it depends on which model you buy
the 40 gig has a much quieter fan as far as i can tell , the 60/80 seems to ramp up after about 20 minutes
but it's nowhere near the terrible din the x box 360 makes
i had the hd-dvd add on for that and although the picture was excellent - transformers is amazing on hd-dvd - the noise the 360 made ruined any film watching enjoyment
overall if the 360 is a 10 and the wii is a 1 on noise , i'd give the ps3 a 5-6 , plus you can always put it in a ventilated cabinet and use a nice long hdmi cable
my sister went to the usa last week to see van halen in concert and brought me back loads of blu rays that i'm currently watching
the picture quality even on old classics like terminator 1 and rambo first blood really is very impressive
for the £300/$300 the ps3 now costs i think most bno enthusiasts could easily afford a toe in the water with this little 'toy'
go on , buy one ! :) you can always tell the wife it's for the kids to play gta on !! :)