I have been putting a lot of time on those sites but not really making the headway I had hoped.
I put an old sound card back into my computer so I actually use two different audio devices.
Sonar and my guitar plugin from Native Instruments use my Motif XS MLAN which is firewire.
Ejamming and JamNow I use an Aardvark LX6 96khz interface that once I changed the buffer size from 512 samples to 256, they both worked perfect.
Have you tried using your internal audio device, you could port the analog into the onboard card, or go out an buy a Creative card x-fi its maybe $40-60 its listed on their site as one that works.
JamNow seems to be more of a launch site for people's music than anybody doing Live jamming, I have 3 songs I wrote and just started playing in sessions on JamNow under N2MUSIC userid. The quality can be pretty good working alone, but I don't hardly see many folks online and none of the ones that are ever want to jam. So I have not had a session with another jammer yet.
Ejamming.com I can't believe they have 11,000 users as I hardly see a handful online and rarely get someone to jam with. It has been borderline workable as the latency seems to be still pretty rough. keeping time is hard. Lots of beginners and I guess just people trying to get the thing work.
I downloaded the vstTunnel but have yet to try it out, seems like they do not give you a real shot at demoing it to its full capacity so I doubt that it is going to be worthy.
Well, the hope of doing some signifcant collabing using one of these sites gets dimmer each day.
Dan