If you put the ABS between the DSL modem and your computers, you'll only need ONE IP address. Leaving all the computers that use the ABS with DHCP should allow you to share files and printers among them, while sharing the single IP address the ABS uses. If you (or your boss) insist on having static addresses, that's no problem, just set them for the same subnet that the ABS is set up for (on the LAN side), and turn off the DHCP server in the ABS.