Agree with OP, i'm baffled... installed ACE 2 but it was a pain in the ass and i still get kicked off most servers.
I'll go back to BF2 Project Reality and wait its arrival on Arma 2, hopefully those guys can sort this mess out, they certainly did for BF2.
Until then It's not worth the hassle, spent 2 hours trying to figure out what to do already and non the wiser... still get kicked