tracert showed the problem was very local.
Microsoft Windows 2000 [Version 5.00.2195]
(C) Copyright 1985-2000 Microsoft Corp.
C:\WINNT\system32>tracert
www.google.com
Tracing route to
www.google.akadns.net [64.233.161.147]
over a maximum of 30 hops:
1 * * * Request timed out.
etc.
30 * * * Request timed out.
Trace complete.
I'd already remotely booted the router.
Always reboot. In this case, I powered down the cable modem and the router, and when everything came back I could get to google no problem. Done.