Jason,
I'm sure more savvy users could give you better answers, but here's a few hints:
1) the 30 day requirement for 25 cameras at 10fps could be immense, exabytes, if you're recording constantly at full resolution with a low compression setting (on the order of 64 terabytes). If they're running VCRs, this might be what they expect. You may need to teach them about motion capture.
If you're doing motion triggering, there could still be a giant file requirement if there's a lot of movement (8 hour days, 5 days a week, movement in front of all 25 cameras is still on the order of 20TB). If the warehouse is mostly still, you could be talking about a few GB a month.... hard to tell.
You also have to contend with bandwidth issues. Even compressed, they're not trivial: 25MB/sec if all cameras are writing to the DB. ATA interfaces can handle the BW, but drives typically can't. You should probably consider hardware RAID 5 with at least 4 wide writing plus parity, that should give you the bandwidth you need. The RAID card should probably sit on a 64 bit PCI bus or PCI-X.
2) They probably want high uptime, given the application. This implies dual power supplies, UPS (or two, one on each power supply input in case one of those goes down - my server has one PS on the UPS and one on the wall); optimally RAID 1 (mirrored data, alternatively use the FTP function in ZM to offsite likely nasty alarms).
3) Processing: from my limited experience, 25 monitors isn't out of the question with typical high-pro server hardware, eg dual xeon 3.06s with a few gig of RAM.
4) You will need LOTS of RAM to store the buffers. You want something that can address it, like a 64bit processor or a PPC, but you might get out past the bleeding edge there. You can probably play with the buffer depths, but Xeon IVs in the right MoBo can address up to 16 GB. You're probably going to need it.
5) Capture hardware. I can't get my stupid pair of ImpactVCBs to work right, so I'm probably not the person to advise on this, but Linux Media Labs is likely to offer good support and this
http://www.linuxmedialabs.com/product_d ... prodid=330 can do 8 streams on one board, probably 16 at 10fps multiplexed. You'd need two cards. I don't know if they play nice on a single PCI bus, but on a MoBo with dual PCI busses, you should be able to put one on each bus. I'd ask them. I tuner claims you can put up to 4 of their Spectra8 cards in a box. That's up to 32 full rate inputs, or 64 multiplexed ones. Pricy, but seems plausible.
OR
Put your server box on gigabit and get a 32 port 100TX/gigabit switch, then hang 25 axis (or other netcams) cameras off it
http://www.axis.com/products/cam_230/index.htm. This would provide a few advantages:
a) no long coax NTSC runs to get all noisy.
b) cams can be remoted on 802.11g for wireless links - all you need is AC.
Unfortunatetly, this is likely to be very expensive, and replaces their entire existing infrastructure.
-David