If you've run into the problem where XP SP2 only allows you to have 10 pending connection attempts to machines, then you'll know this rather kills performance for peer to peer programs such as BitTorrent. You'll know when you've run into this problem, as you can examine the event log and see many "EventID 4226: TCP/IP has reached the security limit imposed on the number of concurrent TCP connect attempts." messages.

Fear not, as this is set by a value in the TCPIP.SYS driver. However, setting it to a different value involves patching the TCPIP.SYS driver. Fortunately for us, LvlLord put together his hard work into a patcher program that will practically remove the limit! You can find LvlLord's hard work over at his home page.