I have one of these in my Media center PC (Shuttle SN21G5, 1GB RAM, GeForce 7300LE, Athlon XP 3200+, MCE 2005). It's pretty good, save a couple of things.
The design of the tuner is such that the tuning hardware is actually connected over USB, like Hauppauge's TV sticks. However, the PCI card has its own VIA USB controller. On leaving S3 standby, the device needs to renumerate, leaving the remote inoperative and the tuners unavailable for 10-20 seconds.
The remote is pretty good, although sometimes goes a bit mental for no apparent reason.
Dual tuning/recording with the T-500 is fairly reliable. Sometimes flakes out, but I blame MCE more than anything.
I couldn't speak for the Hauppauge remote as I use the Microsoft hardware kit, but I've not had mine lockup as yet but then again I don't have the system powering down as it's on all the time.
I do like having BBC3 in one window and then FIVE US in another while chatting on MSN :)