[vasyapupkin1]

I'm considering to buy something like Acer Revo (or any other pre-built system for XBMC) with one non-standard requirement - I want to be able to record (and time shift) analog video.

What options do I have ? Most nettops do not allow to add extension cards...

[Furner]

I'm considering to buy something like Acer Revo (or any other pre-built system for XBMC) with one non-standard requirement - I want to be able to record (and time shift) analog video.

What options do I have ? Most nettops do not allow to add extension cards...

I can speak for the hardware side of the equation.

I would look into the Hauppauge USB WinTV tuners.
Here is a blog that mentions Linux usage in Feisty using the 950
http://lunapark6.com/usb-hdtv-tuner-stic...r-950.html

Many Hauppauge devices have at least some Linux support through independent development. But there are good USB options out there. Pick a few models from Newegg and do some googling to see what people are saying about linux support for various models.
You might need to look into MythTV for backend support for recording. I am unsure as to what extend XBMC will do the live tv gig.