Theoretically if I had $400 just lying around burning a hole in my pocket.... I'd get this HDTV capture card <A HREF="http://www.techtv.com/freshgear/products/jump/0,23009,3410798,00.html" target="_new">http://www.techtv.com/freshgear/products/jump/0,23009,3410798,00.html</A> / <A HREF="http://www.telemann.com/products/dtv200.html" target="_new">http://www.telemann.com/products/dtv200.html</A>. Course to use THAT as a tivo you'd need insanely large hd space... which is part of the reason everyone (tivo, echostar, etc) has taken so long in coming out with their long promised standalone hdtv pvrs.
But seriously, for what you're after. AIW would probably be fine. My old asus gforce 256 sgram with vivo did well for me, though I didn't use it as a tivo (already got a Hughes Directivo which I worship fervently). The new nvidia vivo card I got (chaintech 5600 ultra) does about the same as my old card capture wise. I've known people to be quite happy with the hauppage pvrs and it's hardware mpeg2 encoding.
Probably for your purposes (pvr'ing) you'll be using mpeg2 and you'll be happy with it. I use picvideo mjpeg (at quality level 19) which produces large files but MUCH smaller than raw avis at almost raw avi quality. But I use it to do still captures to make stuff like wallpapers and clips of scenes I enjoy. Avi is also an easier format to edit, something you're probably not planning on doing. If you're just using it to simply watch a tv show, it's not a difference you'll much notice and you'll save a ton of disk space.
I capture using virtual dub which I keep as an active window while capturing. (I've got a powerful enough system that stuff in the background usually doesn't cause me to lose frames) If you want to capture stuff in the background while doing other stuff.. particularly stuff that is very cpu intensive., you may find a standalone card that does mpeg2 hardware encoding quite useful. Besides, regular avi encoding is always there if you need it (well, on most cards).
Also the most important thing in video capture is the input you give it. Different cards might give you different stuff (hardware compression, a nice software package, better driver support) but in the end the overall quality of the recoding is only as good as what you put into it (analog tv reception, cable reception, sattelite/digital tv reception). Don't overpay! If you really want to upgrade the quality of the recording, the best investment is upgrading to digital cable or sattelite.
And checkout this site, you'll probably find some useful information there. <A HREF="http://www.tv-cards.com/" target="_new">http://www.tv-cards.com/</A>
And finally. If you do find an extra $400 lying around. Think you could pick me up that card I mentioned above? =)