I'm kind of in the same boat...looking at my options for desktop video. Here's what I've found.
If you want to hang onto your current Geforce2 card, there are a number of PCI cards that will let you do video capture/editing. Comes down to how much you want to spend and what features you need. Are you trying to edit digital video (DV) from a digital video camera or do you need to capture analog video from a Hi8/VHS/TV?
Dazzle DVC II (for around $250) seems to be a popular choice and let's you do real-time hardware MPEG2 encoding at DVD resolutions. So far as I know, it doesn't include TV tuning capabilities (standl-alone TV tuners are pretty cheap though). However, I've read in various desktop video forums that bundled software and support is pitiful.
ATI All-In-Wonder or even the 64MB VIVO is another popular choice. Main difference between the VIVO and the AIW is the AIW provides a TV tuner and has SVIDEO-input. If you're also looking to upgrade your video card and want something that can do video in/out, this might be your choice. Most problem complaints seem to be related to dropped frames and loss of audio-sync while capturing at high resolutions (the MPEG2 encoding is apparently done in software -- though it might use the ATI's IDCT hardware for acceleration -- so it's alot more CPU-intensive than with the Dazzle).
If you're not interested in video-out (maybe you're interested in creating VCDs or SVCDs or maybe even DVD-Rs), you might look at the capture cards offered by Winnov.com. Their low-end cards ($100-$250) seem to be aimed at video conferencing but they are capable of 30fps capture at DVD resolutions as well. Nice thing about their AV series cards is that they provide on-board audio hardware so video and audio are guaranteed to stay in sync (the ATI and (I believe) Dazzle cards rely on your soundcard to capture audio...the result being that sometimes audio and video can get out of sync). I'm not sure if these guys offer real-time MPEG2 encoding though. They offer a number of encoding formats but you might have to first capture to AVI then use something like virtualdub to convert to MPEG2/4 or whatever.
Other dedicated hardware to consider might include the Pinnacle DC10.
One other thing to keep in mind is that video capture is fairly disk-I/O intensive. Depending on resolution and compression, 10-15MB/sec bandwidth isn't unheard of. So you'll need plenty of fast hard drive space.