I tried their support line first.
They said that model is no longer supported and I would have to buy a new system.
Many of these security DVRs are sold with no hard-drive installed, allowing the purchaser to install a drive themselves. This is why I was thinking it was simply a "plug and play" affair.
I've been reading over this site. Though it is a different brand, I am hoping my unit will be a similar job.
http://www.cctvcamerapros.com/DVR-Hard-Drive-Installation-s/218.htm