hmm, which fan now..

[Hellsthief2.0]

hey guys, my name is patrick. i built a bad ass p4 2.4c system a few years back that was overclocked. so its got big ole fans in it and now (helocopter style).
i wanna give it to my aunt for her kids to use as a media computer. So i want it to be nice and quiet for them to watch movies ect. atm i have some huge 80mm thermaltake highspeed fans and a 92mm highspeed CPU fan on a huge copper thermaltake heatsink i think it was called tornado (it fit 92mm fans and 80mm fans). I would like to not have to change the heatsink out if i dont have to just cuz im a lil lazy with computers that im not going to be using personlay lol. so if there is a silent fan i can put on that heatsink that will do the job that would be great. if not ill have to man up and change it out. also i wanna swap the casefans for something quiet but effective. it is gunna be stock speed when i give it to them. also, the northbridge fan craped out awhile ago and a jurryrigged a fan to it. (i was very proud of that when i did it lol) but i would like to give them a new one just so it doesnt die on them.
Anyway if you guys have suggestions on fans or brands to look at i would really apreciate it. thanks so much for your time.