Here is the registry entry...
HKEY_USERS.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Internet Settings
"MaxConnectionsPerServer"=dword:00000020
"MaxConnectionsPer1_0Server"=dword:00000020
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
"MaxConnectionsPerServer"=dword:00000020
"MaxConnectionsPer1_0Server"=dword:00000020
It's one of the 2... change the dword # to the amount of connections you want to allow at once. Just so you know there is a reason it is set to 2... per HTTP specs, the limit is 2, now rarely does this ever cause a issue, there are a few websites however that wont handle more then 2 at once.