you might need more HDD space for sure. I would also separate the the OS/APPS from the data so you need at least 2 drives, one for the system and one for data.
integrated graphics will be fine. a 6 core CPU is over kill, a dual core will be fine, quad at the most. same with ram 4GB is plenty as the GV card and software only support 32 bit windows (XP or Vista, not sure if 32bit Win7 is supported.
do you have a budget in mind?
a i3-2105 or dual core AMD, or maybe one of the new A8 APU's
is you have the $ I would go with a boot drive and then 3 x 2TB seagate or WD "green" drives in Raid 5.
if this is a budget build then a boot drive and 1 of the above "Green" drives
"High compression/storage ratio--approx 3 gig per color camera per day @ 24 hours a day of recording" x 16 = 48GB/Day = 19 days of storage. 2TB would give you a month +
the MB would depend on how many GeoVision cards you will run, they require a PCIor PCIe x1 slot depending on the version.
$500 for all components, until now I know the budget.
Phenom II X2 555
2GB RAM 1333
Mobo, maybe with AM3+ socket for future CPU upgrade
Case and PSU 300W generic
The cameras will be recording 24/7 continuous.
then you need to think about 2 GV cards with 16 cameras.
also, I wouldn't worry about a AM3+ MB the software only supports 32 bit OS, so better processors and memory over 3.5GB won't help. save your money.
get a solid PSU like the Antec 380w or Xigmatec 400w, these are cheap and reliable.