After years of struggle with Tcp/Ip patches, Microsoft finally remove the half-open connection limit.
Since Windows XP SP2 Microsoft limited the maximum half-open connections to 10 only. this limitation have caused many file-sharing applications to slow-down their download rate, and Event-id 4226 has flooded the system event log.
In Vista SP2 this limitation is finally gone! you can read more about it in this KB969710 Article
Windows 7 is no longer limited by default.
How to Remove TCP/IP Limitation in WinXP SP2-SP3 and Vista RTM-SP1
Those of you who still works on older versions of Windows (Vista/SP1, XP-SP2/SP3) can use
the following recommended utilities. These tools are also referred as:
Event ID 4226 Patcher, EvID4226 fix, TCP/IP Patch, TCP Half Open Connection Limit Patch
1. Lvllord Event ID 4226 Patcher (4226 fix)
Please note the instructions on each utility. Some of them includes different versions for 32bit and 64bit Operating system environment.