You might try posting your question on the www.linuxforums.org web site. There are a lot more people following and moderating that forum these days who might be able to answer your question. Also, please be more explicit as to what you are trying to do, and what you mean by "video decoder". There is quite a bit of scope for confusion in that term.

I agree with Rubberman.
Also Look at Video4Linux project: http://linux.bytesex.org/v4l2/

The linux kernel supports the cx23885 chip, so you should probably be looking at video4linux. I have of course no way to guarantee that your concrete card will work, even if the chip is supported.

ATOM based? is it a netbook or something like that? i ask because i'm interested in to buy one too and thought someone have a good hint for me.