Well, apparently in service pack 2, there is a system file that limits TCP/IP conections from infinite, as it was in SP1 to 10. The logic is, if a virus was introduced into your system, by limiting the number of simultaneous connections accessible, it would slow the work spreading. I guess in P2P apps, it limits te number of connections you can make at one time, effectively slowing down DL/UL speeds.
I applied the patch after some moreresearch, and it does seem on the ol' buttdyno that it is a bit faster while running BT, and surfing the net.