Security Camera-to-DVR Setup on Linux?

mrperkins asks: "I have been asked to help a friend setup a Linux DVR (Digital Video Recording) system for security cameras. Previously this has been done on Windows XP using Avermedia video capture cards from the MP3000 and MP5000 series, and using their bundled software. They have a Linux version but the software is horribly broken. The Windows software allows playback/recording/backup from 4-16 cameras. This works reasonably well but certainly has it's share of problems - the PC's hardware being only one. Can this be done on Linux using Free Software and compatible hardware? I have heard that the frame rates achievable under video4linux are simply too slow, but I would like to prove otherwise! Are there any software packages that can do this kind of thing (not just a single stream but a fully featured package)? Also, what cards (pref. up to max $200US) would you recommend? If anyone is already doing this kind of thing please let me know what you're using!"