I have tried 4 different TV Tuner cards. My first one was a creative labs digital VCR, Card worked great but very low resolution, software was flawless.
I then tried both an Avermedia Ultra TV USB 300, great box, and an ATI TV Wonder Remote Edition. Both had really good quality, and I loved some of the features of the ATI -- Like the ability to set up the Live TV Image as full screen and semi-transparent, so you could watch full screen tv while working away on the computer. The problem with both of them for me was recording software. If you were veiwing live TV everything usually worked, but 80% of the time my shows wouldn't record because the program had crashed, or the software wouldn't run if the computer was locked. Also I use VNC and I would have to re-boot everytime I logged off of VNC in order for the recording software to work. In short just too many problems with it.
I now have a hauppauge PVR-250. Great card, software -- again not so great. Basically in order to get the card to work you have to install, the windows drivers, PCI Drivers, MPEG Decoder, WinTV Software, and scheduler program. The quality from the WinTV program leaves quite a bit to be desired -- even when recording on so called DVD Quality, and the biggest problem is again the scehduler. I have about 50 messages to and from their support trying to get the thing to work. Basically after using the scheduler software for a couple weeks it will suddenly just start popping up errors and refuse to allow you to scehdule any new programs, in order to fix it they told me I had to run their cleanup utility, which removes all traces of the drivers/programs and then you have to go through and install everything again, and reschedule everything. Having to do this every few weeks was annoying, there was also a problem where the scheduler would crash if you tried to have more then 8 programs scheduled at once. There was apperently a fix for this, but I haven't bothered.
I have also tried BeyondTV and SageTV, both of which I found to be rather chunky, and flakey. They insist on being open/minimized to record rather then just doing it in the background. I found them to be a nusience to navigate in and iirc at least one of them has guides only for US cities, which does me no good being in Canada and all.
I now have my card installed in a Media Center 2005 PC and am using the built in TV software, and I have to say I am impressed, I don't get to spend much time watching tv so I like to record all my shows, I have yet to miss one recorded by WMCE 2005, it records in the background without bugging me, you get a little Red Circle beside your clock and thats it, it lets me lock my computer and use VNC no problem, the video nevers noticiably skips or misses a frame, there is a built in TV guide (that includes Canadian cities, unlike some) and quality is a huge leap over the WinTV software.
Maybe I'm picky, but if I go out and spend $250(can) on a PVR card then I think it's resonable to expect the software to work relativly well and to not have to reinstall every couple weeks because of errors in the program (A LOT of people were having problems with Hauppauge's Scheduler program).
Just MHO on the matter.