Forgetting workflow and just concentrating on backing up the photos, I have them firstly on a drive in my computer other than the system drive (I use the system drive solely for apps and windows files). Then, as soon as they are off the card and on the drive, I copy them to a nas setup for safety.
I bought a $50 Linksys NSLU2 NAS box for the job. Basically, it's a tiny (smaller than a paperback book) little box that allows you to connect two USB drives to it. I have a 500gb and a 750gb drive connected and I use this as central storage for all of the computers on my network. You can also use it as a pseudo-raid setup by having the first drive copy itself to the second drive every night, but I'm pretty sure two copies work just fine.
There's a HUGE number of NAS boxes on the market now - most don't get good reviews. The one advantage to the NSLU2 is that it allows you to use any USB external drive. You need to update the firmware to the latest and greatest BEFORE attaching drives. That will allow you to use FAT32 or NTFS drives - which in turn allow your windows machines to read them directly. Otherwise, since the NSLU2 is a linux device (with a TON of linux distros for you to replace the on-board one with), it will format the drives EXT3, which means if the NSLU2 dies, you'll have to hook the drives to a linux box to read them. The fact that it's linux will have no bearing on you using it, however.
I simply map drives to the the NSLU2 and use synctoy from MS to replicate to the NAS. Cheap and easy.