If your ISA server has a default route to the ISP router, then you need to have static routes for your LAN networks pointing to the next-hop on the internal interface(10.0.0..x)
route add 126.96.36.199 MASK 255.255.254.0 10.0.0.x(next-hop of internal interface) -p
route print will show your routes
Also, its safer to never post your public IP range.
If you have any question you can e-mail