Windows Service Pack 2

From AzureusWiki

Windows Service Pack 2 (SP2)

Limited number of simultaneous incomplete outbound TCP connection attempts

SP2 imposes a limit on the number of simultanious new outgoing connection attempts pending at any given time (10). This should have no affect on downloads, other than to perhaps slow down the rate of new peer connection establishment. If you've got many connected peers, and green health, then the problem likely lies elsewhere.

For details see: http://www.microsoft.com/technet/prodtechnol/winxppro/maintain/sp2netwk.mspx#XSLTsection127121120120 and http://www.lvllord.de/?lang=en&url=4226patch/faq

Windows Firewall enabled by default

SP2 installs have Windows Firewall enabled by default, which can cause connectivity problems if not opened for Azureus. For details see: http://www.microsoft.com/technet/prodtechnol/winxppro/maintain/sp2netwk.mspx#XSLTsection130121120120