Windows 7 comes configured to only allow for 10 connections by default. This is supposedly a move by Microsoft to cut down on malicious software inundating the web and killing bandwidth. For the everyday user 10 connections is probably ok, but for us, we need more power.
This tool will patch your tcpip.sys file and allow as many connections as you want, 100 should be more then enough though. Grab a copy of Half-Open and give it a try.