Since there isn't many 5400rpm (or 5760rpm or whatever) drives available and those who are don't have the top capacities, one might have to go for a 7200rpm drive.
There is 300GB Maxtor MaXLine II and 300GB Maxtor DiamondMax 16 which are both 5400rpm. MaXLine II is with ball-bearings and while my 1-year-old doesn't whine (much) yet, some other sample might whine (even this sample might whine after another year of operation). DiamondMax 16 should be FDB but I wouldn't bet on it. (Like MaXLine +II and DiamondMax +9 are identical, I though so might be MaXLine II and DiamondMax 16... or at least early drives of that series.
...I just checked the DM16 datasheet. It's like I was afraid of.
With BB: 4R060J0 4R080J0 4A160J0 4A250J0 4A300J0
With FDB: 4R040L0 4R060L0 4R080L0 4R120L0 4R160L0
J-BB motors, L-FDB motor
FDBs are only available with capacities up to 160GB. BBs are available up with 250GB and 300GB capacities as well as low capacities. (MaXLine II is available only as 250GB and 300GB and with BB. There's no doubt they are identical to DM16.)
So, if the drive is a long-term investment, I'd probably stay away from MLII/DM16 as they might develop a nasty whine over time. These drives have 4 platters but they don't vibrate much.
Going for a Hitachi 7200rpm drive might not be a bad idea as they do support APM which allows reducing rpm while idling. Some quotes from SPCR's 3-platter 7K250 (& DM10) review: "The noise characteristics of this drive in Low RPM Standby are comparable to many notebook drives. At 60% of full speed, the spindle speed is approximately 4,200 RPM and its first harmonic occurs at ~70 Hz; most people are less sensitive to this frequency than the 120 Hz that the drive produces at full speed. Power draw also drops dramatically, down to notebook drive levels.
Vibration was comparable or slightly better than the lowest vibration 3.5" drive in our lab â€” almost notebook level. The lower frequency of resonance at this level made it difficult to hear even on our resonance-amplifying test box. Only the pickiest silencers need worry about vibration at this level."
5-platter 7K500 review here at SPCR:
"Perhaps because the 7K500 has so many platters, the reduction of noise wasn't as complete as it was in the other models (the 7K250 and the 7K80). The whoosh of airflow didn't disappear to the same extent, although it did sink to about the level of our reference Barracuda IV."
Since Deskstar T7K500 (or Cinemastar 7K500) are Vancouvers, they are likely closer to 7K250 than 7K500. This is not guaranteed but likely.
Especially if the HDD is on always when the PVR is powered on, APM will be handy as it doesn't depend on PVR to offer spindown support.
EDIT: just fixed typos.