Samsung SP1614N (160GB, 7200 rpm) quiet like a whisper, seek noise (and speed) can be tuned.
Samsung SP2514N (250GB, 7200 rpm, ATA133)
Seagate Barracuda
250 GB IDE WD Caviar WD2500JB (hot, a bit noisy and VERY rarely some pixelation, didn't bother me however)
160 GB IDE WD1600AVJB
320 GB IDE WD3200AVJB
500 GB IDE WD WD5000AVJB (this is an AV drive specifically designed for HDD recording by STBs, relatively cool, very quiet, no pixelation, quite fast, not much more expensive than a regular drive... overall perfect !!!, so far
Seagate ST3400833ACE (400GB, 7k2 RPM, 8MB Cache, DB35.2-Series, especially designed for PVR)
Seagate DB35 ST3802110ACE 80gb especially designed for PVR