using windows xp
1. check ur web server: open internet explorer in ur pc that host ur DVR card, login and see if u can view the cameras
2.if 1 is good then connect ur host pc to hub/switch( i'd rather choose switch),
then plug ur client pc too, disable all firewall (not recommended) in both pc, and then open host pc ipaddress in clients pcs internet explorer, login and u will see the cameras
3.plug ur router for internet access to the hub or switch, configure the DMZ of ur router(not recommended) the ip address of ur host pc, and setting (see ps's), make sure your host pc can open internet (try googling), and done. to test that u can see ur host pc by internet, open internet explorer with other connection(not in same connection with ur host pc) eg: try in ur home of other office. type ur router PUBLIC ip address (not like in LAN) in ie and very done.
ps : make sure u are (host pc,client pc,router) in thes same subnet
ps : make sure u give the gateway and dns in cliend and host pc is the ip address of ur router