A few weeks ago I reported a mysterious problem with capture from a WinTV card: every few minutes, the card would silently drop a single field when capturing at 640x480 or similar.
As a result, the field order of the captured clip seemed to reverse periodically, wreaking havoc with things like inverse telecine etc. With this bug, the card was nearly unusable (definitely impractical) for full-resolution capture. Well ... problem solved!
I replaced the Hauppauge driver (latest VfW driver for Win2k from their Web site, w2kdrv311.exe) with the open source WDM driver for BT8xx cards (version 5.2.2), found here: http://btwincap.sourceforge.net
It works fine with VirtualDub under Win2k, despite its WDM nature. Regardless of what the author says, I did not need to recompile on Win2k. Also: I have a dual CPU system - the author went to great lengths to make the driver SMP-compatible, evidently with success.
Two minor issues:
1) the Hauppauge applications (WinTV, WinTV Radio) break. (WinTV never worked for me on Win2k anyhow ... "error initializing hardware")
2) You need a DirectShow capture program to get access to all the settings of the driver (e.g. to change the video standard from NTSC to PAL). The included capture program, AMCAP, does allow you to watch TV, listen to the radio, and to set up the driver.
It is quite buggy, though - I think it is little more than a M$ sample application from the SDK. Highly recommended!