If you have been receiving:
Event ID 4226: TCP/IP has reached the security limit imposed on the number of concurrent TCP connect attempts.
or you plan on using any sort of BitTorrent or setting up any sort of server.
Tweak Tcpip.sys on Windows XP
1) Visit http://www.xp-antispy.org/index.php/lang-en/download and download “packed zip archive” for your language (filename is like “xp-AntiSpy_english.zip”)
2) Extract the zip file downloaded (Click “Next” -> “Next” -> “Finish”)

3) Open the new folder created  and double click on the exe (something like “xp-AntiSpy.exe”)
4) Goto (in the top menu) “Special” -> “Connection Limit…”

5) In the new …