In order to hit the higher speeds using HSDPA, you need to ensure that Windows is configured optimally. Specifically, you need to ensure that your TCP settings are up to scratch. Here’s a quick run down of the right settings to get you up to those higher data rates - these settings will be good up to 7.2Mbps

You’ll need to change the settings the in the registry. If you don’t know a. what the registry is, b. what TCP is or c. what the capital of Bhutan is, then this hack isn’t for you. If in doubt, don’t do it.

Disclaimer over. So the keys you need to tinkle with are in:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

For all devices, or if you just want to change the settings for individual devices, they’re held in:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces

The optimal settings for high speed operation are:

This only applies to Windows 2000 and XP - Windows Vista is apparently smart enough to change it’s TCP settings on the fly.

Enjoy.