Don't be concerned by your choice of hardware, that system is by far and away more than capable of running a demanding Geovision system. For a long time we used Athlon socket A, then 754's,then 939's & now AM2's. Whilst Geovision them selves don't test AMD based hardware, they do accept that in general few problems will arise - In fact many recent issues with card stability has been related to bad Intel chipsets.
Using H.264 compression you should expect 1.5Tb to last you a good month if not more when working on a VMD basis. If you’re talking time lapse, then considerably less.
As an example a typical system for us would use a 3000+ athlon64, 512mb DDR, and a motherboard with integrated graphics (ATI). We've used this same setup on everything right up to 1480 combo cards - no issues.