I have two freinds who are positive and find themselves in the same situation, as YN2k and Gamrican have said, the guys who run off aren't worth it anyway... and are probably doing you a favour by removing themselves from the scene.
Some of the excuses have been all the way from 'don't want to catch HIV' all the way to 'dont want to see someone I care about get sick' - and they end up missing out on some of the most sexy,wonderful guys I've ever met... because they can't get over the fear.
I'd have no problem dating a HIV+ guy, particularly one who looks after himself and is control of his circumstances, and in particular is honest with me.
As YN2k said, its a numbers game, so - you're HIV+ and not interested in just partying and having sex? - theres bound to be more guys like you out there, BUT you need to be out there to find that other guy.