I'm running an Koolance EXOS-2 LX external liquid cooling system. Both the processor (QX6700) and northbridge are cooled. As of right now, the processor is running at 3.2 Ghz, multiplier is locked at 10x, and the bus speed is at 320 Mhz. The FSB is at 1281 Mhz. I'ts an Asus P4W-DH Deluxe mobo.
My Geforce 285 and 8 gigs of corsair dominator (PC2-6400 800Mhz) ram are just cooled by the case fans. I have two 120mm stock case fans in the front, and one stock 120mm case fan in the back on my Lian Li case (BEST CASE I HAVE EVER OWNED).
Temps as of right now (centigrade):
CPU: 31
Northbridge: 44
Cores: 54, 52, 50, 48
HDD: 34, 26, 37 (the 3 that do have temp sensors are two WD 500 gigs and one seagate 1500 gig, I have 3 more also, two WD raptors and one old WD 200 EIDE gig)
All of the hard drives line up in a very nice, well designed rack in the front of the case and are cooled nicely by the two front fans. I leave my case fans on max speed all the time, and I leave my liquid cooling radiator fans on 7/10 most of the time, until I'm doing some serious gaming and I turn it up to 10 if necessary.