I've tried a bunch of foreign systems like X-Fire. :)
The biggest problem with these programs is that you can't play with someone who has a bad IP address!
And Hamachi was specifically created to solve the problem of indirect IP addresses by creating a LOCAL (not global) network!
And programs like X-Fire, with their cool and (sorry) usually buggy interface, aren't really needed for those who have a direct IP address – you find an opponent on ICQ, find out their IP address, and they create a game.
The advantage of a community like X-Fire is that you can find opponents from other countries and try yourself out on non-standard maps... otherwise, everyone plays almost the same map and thinks they're the best. ;)