However, individual computer connected directly to modem works.
Hmmm...this doesn't sound right.
Just to be sure.
I assume that you've got two wired connections:
a) Ethernet cable connected from DSL modem to "Internet" jack on Linksys.
b) Ethernet cable from Linksys to Vista computer.
c) Ethernet cable from Linksys to 2000 computer.
d) No connection from the modem to EITHER computer.
e) Power adapter plugged in for Linksys.
Please double-check to see that you've hooked up this way.
EDIT - BTW, to access the router (Linksys), just type "192.168.1.1" (no quotes) into the browser address bar - NOT http.
EDIT2 - OK - http:// will work; not needed, though!