Hmmm... have a read of this. It suggests to me that Avolve are using trafffic shaping technology & this may well be why your downloads are so, so slow.
http://www.logisense.com/pr/engageip.pdf

As for your adapter, I don't have a clue but I don't think it would be causing a firewall problem?? Somebody else may know! As long as your XP firewall's configured correctly & you aren't using any other connection devices (high speed modems & routers often have an internal firewall)... I really don't know where your firewall would be coming from. Did you get any firewall protection from your ISP when you upgraded from dial up?? Just double check that you don't have a second firewall!

You could try changing ports, there are instructions within the satellite thread I gave you earlier.

Damn... beaten again.