If it's wired, then you should be able to simply plug in with a cable. Assuming it's serving DHCP addresses and isn't MAC locked, then it'll give you an IP address fine. You might like to turn off your wireless card if there's any possibility of being in range of your usual network. If the router won't let you in, you'll get an IP address beginning 169. (running ipconfig from a command prompt will show you this).
XP is a pain in that it'll lose any custom existing connections you have set. It's no problem with DHCP, however if you usually have custimised network settings (such as fixed IP), then XP will forget these if you make another network connection.