My current development machine is Windows XP, and I use a modified tcpip.sys to allow me to exceed the 10 connection limit built in to IIS. I know that Vista's IIS has the same limit.
Can anyone confirm whether this connection limit is present in Windows 7 IIS as well?
From the base OS perspective, the limit has gone.
With Vista pre-sp2 it depended on the version. See https://stackoverflow.com/questions/413110/which-is-the-maximum-number-of-windows-concurrent-tcp-ip-connections/929973#929973
Since Vista SP2 the limitation have been removed from TCPIP.SYS, and has been configurable through a registry key. Windows7 should follow that same behavior (source and for 7, and here), but of course we will not know for 7 definitely until RTM since appart from technial there may be license restrictions.
However, IIS introduces its own limitations, depending on the version of the OS. For Windows 7 this limit is between 3 (Home Premium) and 10 (Business, Enterprise & Ultimate) simultaneous connections . Depending on your scenario, it might help to lower the connection timeout to free up slots sooner.
The connection limit in IIS is NOT THE SAME as the 10 half-port open limit. This is a limit built into IIS and has nothing to do with TCP/IP. Pay for server or run Apache.
There is a special version of TCP-Z, a tool for "patching" tcpip.sys, for Windows 7 - an indication that this setting still exists in Microsoft new operating system.
Disclaimer: it is not advised to change operating system drivers.
Edit: I stand corrected, there is a 10 concurrent connection HTTP limit, confirmed by testing.
Pleae see this link, and how to get more concurrent connections in IIS.
http://community.psion.com/knowledge/w/knowledgebase/1227.a-r-c-increase-iis-connection-limits.aspx
Regards