xp pro 2000 server over udp

If anyone can help I’s love it. My kid want to play starcraft over our home network. Starcraft requires IXP or UDP over the LAN. We have one computer running XP Pro and one running 2000 server. We have no problem conecting using TCP/IP but of course Blizzard doesn’t use TCP/IP. I think it might be port problem but what ports do I need open?