Connected new DIR-655 router and one XP computer could not get DHCP address. Multiple other computers worked fine. Eventually tried disabling DHCP in old router (WRT54G) and inserting it between the Pro/100 and the DIR-655 and it worked. Computer was addressed by the DIR-655.
I assume the issue is some capability of the DIR-655 that isn't handled by the Pro/100 but is NDHCP forwarded on by the WRT54G. I'd like to know what to turn off in the DIR-655 to get it to work directly with the PRO/100.