I've unsuccessfully tried to find details on the optimum number of VPN

Client connections for a BM 3.7 SP2 server running NW 6 SP3. Our WAN
link
is a T1 to a Cisco 2611 router, then to a Cisco 2924XL Switch, a Dell
2650
Server (BorderManager/VPN Server), then to a Cisco 2924XL Switch, then
to
a Cisco 3640 Router and finally our Network.