I get the feeling with Ubuntu I may never need to build a custom kernel again... Hauppauge WinTV tuner card plugged in, a bit of userspace messing around, apt-get install tvtime, and hey presto - TV on my desktop.
Something is a bit dodgy though - until I ran tvtime, I couldn't get any sound output from the card in mythtv, xawtv or mplayer. After this, myth seemed to work flawlessly. Need to look into that.
Another mplayer command for those who might be interested:
mplayer -tv driver=v4l2:device=/dev/video0:input=0:volume=50:amode=1 -zoom -ao esd tv://
Getting the QuickCam Express to work with Mplayer in Ubuntu:
1) Enable multiverse in your /etc/apt/sources.list
2) apt-get install mplayer
-Select the appropriate optimised package for your CPU and install that via apt-get install
3) mplayer -tv device=/dev/video0:driver=v4l:width=320:height=240 tv://
or to allow the window to be resized:mplayer -tv device=/dev/video0:driver=v4l:width=320:height=240 -zoom -vf scale -sws 2 tv://
Update 2. You don't need to build the whole kernel source before being able to compile the spca5xx driver - I interrupted the kernel build after about 1 minute, then was able to build the driver successfully.
Update: you only need to install 'linux-tree' and the other kernel source dependencies will be pulled in.