Yup - that Vantec is the quitest 60mm I've seen. I've got their 92mm.
I've got my HTPC very very quiet, but would love to hit *silent* someday

. Right now, my refrigerator in the other room drowns it out, as does my projector when its on. Under total silence, it can be heard if you try to, but even then only barely.
Here are some tips that helped me...
For a hard drive, look at the 24db Seagate Barracuda IV.
For 80mm fan's, I'm using 3 "PC Power & Cooling Silencer", better on paper than Panaflow and I found them locally. I use one 80mm for intake in the rear (I needed this for cooling - I wish I didn't). I replaced the 80mm fan that came with my Heat Sink/Fan Combo. I replaced the 80mm fan in my Enermax dual fan power supply (in addition to the quiter fan itself, this PS has a knob to adjust the speed of the 80mm fan).
The Enermax power supply also has a 92mm fan, which is pretty loud (for a PS marketed as "quiet"). I replaced this 92mm with that Vantec (20db) and replaced its heat sensor with a manual knob (this may have been overkill as the fan is very quiet and is not directly exposed to the outside).
I also lined my HTPC's case with 'Dynamat Xtreme' insulation. It's used on doors and trunks of automobiles to insulate them from road noise to improve the performance of the stereo system. It elimintes a lot of vibration found in the light metal of our HTPC cases. I noticed a significant improvement - it completely eliminated ANY remaining noise from my Barracuda HD.
-Jeff