Trouble connecting to SQL Server on Windows XP SP2?

Thanks to the firewall installed by the default XP SP2 installation, you'll have to remember to enable ports 1433 and 1434 (UDP) to be able to see your SQL Server from elsewhere in the domain--or turn the firewall off (at your own peril). Note that you can tell the firewall that you don't want the ports to be made visible outside of your subnet (a good idea). That way only people on your own domain can trash your server... ;)