Ganz make some very nice DVR's aliong with Samsung Techwin. Try and avoid everfocus as they do tend to be quite over priced.
Depending on how many channels you need, samsungs range improve with features with the more channels you require.
At present you most likely have a time lapse VCR, a multiplexor, and a quadplexor
Quadplexors allow you to view four cameras on one screen in quarters, whereas multiplxors encode the video0 feeds in to one stream so they may be recorded by the time lapse VCR's.
Nowadays with the arrival of DVR's these features are built in so all you need is the DVR, cameras and a suitable amount of storage.
Just note that alot of people forget to set the DVR to overwrite the data when the hard drive is full which in turn then displays a hard disk error resulting in panic! so just be sure to take the time to read the manual and configure it correctly
Many advantages are given when upgrading to a DVR such as
Remote connecting so you can view your cameras over a LAN or WAN, Alarm outputs so you may link the DVR to external devices.
Cameras have also evolved ALOT over the past decade or so.
I would strongly recommend visiting samsungs website and reading through the glossary of features on their equipmnent which will give you a better idea of what options are available to you. once you have picked out what you want it all to do, let us know and i may be able to point out some equipment for you
Hope this helps