If your Connections Pane shows more than about 6 hosts, that means the code has decided your connection is good enough to serve as an Ultrapeer, handling about 6-7KB/s of gnutella traffic. Congrats.

If your other internet activity slows down, just reduce the upload bandwidth to about 85% in the slider tools->options->uploads. That should prevent any noticable lag when browsing or doing email.

cheers (if you need more info, check out the forum rules for what specs help)