In terms of MPEG2 hardware encoding, the only ones I know of are Hauppauge's PVR cards - PVR PCI (no longer supported), PVR-250 and PVR-350. The only problem is, there are some image quality issues, though this can be tweaked, and there are considerable driver difficulties to be overcome by Hauppauge's developer. And yes, developer is singular - 2 pieces of evidence. One was in an e-mail from Hauppauge, stating that "their developer is busy with other projects" - and the second is just that their driver releases are far-spaced, and they usually don't fix as many problems as they create.
Great praise there for the products there, eh? For the record, I do have a PVR-350, and it does work. I don't know that the quality is the most excellent, but I think that it is better than a VHS, but not DVD quality. I record TV shows, then edit the commercials out of the stuff I want, using Ulead Videostudio 7, and put them on DVD. Even after that re-encoding, it still looks good.
Click the second link in my sig for the SHSPVR forums - probably the best place to go for info/help with Hauppauge products. Bear in mind, it is a much smaller forum than Anandtech.
I'll echo what has been said too, and say that a videocard, in terms of just outputting to the monitor, not the capture part, will not speed up rendering of edited video - the CPU does the rendering/encoding, so you'll want a fast one, like a fast Pentium 4. High bus speed is a plus too, and a fast hard drive or even a RAID array can just help the work go faster when dealing with big video files.