US Magtheridon Horde has probably the biggest community of boxers, through it is a PvP server.

I personally care for the PvP stuff, but I've found that once you get through the leveling process (a pretty small portion of your overalll play time) no one ever bothers a 5-boxer. Course, I never bother anyone else, either. There will definitely be moments of frustration with jerks, but if you mentally accept that going in an expect to need to log on other teams at various times, it really isn't that big a deal.

Anyway, if you try it out message any of us in the Zerg and we'll set you up with starting gold and make sure you are set to start.