i'v had 0 (zero, ziltch, none, absolutely nothing, -1 +1, goose egg) problems with jazz and xp.
just unblock jazz.exe from the windows firewall and open ports 10052-10054 TCP and 10052 UDP.
make sure u also get sp2 for xp, because the older firewall from oem and sp1 isnt the same.
pm me if u cant find out how to get it