Vista desktop XP laptop problems

I've looked everywhere and tried everything I can think of and have found . . .

I had a Vista desktop wired with an XP laptop wireless, printer shared on vista desktop and shares and printing worked fine.

I changed DSL modems (old one was bridged) . . . could on get new going by leaving defaut settings and setting wireless router to DHCP.

Now vista desktop is wireless and xp laptop still wireless and I can get to the xp laptop from the vista desktop but not vice versa.

Turned off all firewalls, joined to the same workgroup everything . . . does not make sence . . . any help or ideas would be greatly appricated.