I have looked at Zoneminder, but I am hesitant on which hardware capture card to purchase. And I don't know the hardware requirements on recording (and streaming) eight feeds.
I'm in the process of setting up a DVR for my family and I've observed that very few (if any) support GNU\Linux. They all advertise to have "web clients", but all these require ActiveX controls. They do "support" Firefox through IE Tab and Mac through plugins, but that's it.
So 1) use caution if you're a non-Windows user, and 2) I'd be interested to hear of a good system that does support GNU\Linux.
I will probably end up rolling my own with Linux and Zoneminder.