HDTV PVR: The best HDTV card for recording HDTV from a cable provider?

[any ANONYMOUS forum user]

What is the best HDTV card for recording HDTV from a cable provider.

Here is my situation
My cable provider provides unencrypted QAM HDTV content.
I have a 3TB ReadyNAS that will stream video, exports samba shares, http, https, ftp, you name it
I have 3 HDTV's
I use mostly laptops so usb might be best, I do have a couple PC's I could use if I had to.

I want to build a media center or some kind of my own PVR setup so that I can record and play back content. The ReadyNAS Network Attached Storage has a usb port and runs on linux, so in theory I could even record directly from that box.