DrTCP

DrTCP is a small, yet reliable utility designed to optimize the Internet connection for Windows 2K and XP users. It alters TCP parameters, possibly resulting in a huge difference for your download speeds.
TCP tuning is an operation that’s difficult to accomplish. The techniques involve a great deal of network knowledge and might often result in lower performances even when managed by advanced users.
DrTCP is an easier approach to tweaking the TCP settings for smoother Internet speeds. It provides access to a specific area of the computer registry that stores TCP options.
The first noticeable advantage is that there’s no installation process. DrTCP is portable, which means you can run it from a removable drive on any machine, without leaving a footprint on the registry settings.
Even though it may appear easy to work with, this is just the first impression. DrTCP is aimed at advanced users, so beginners should not let themselves fooled by its simple appearance. Applying changes to the registry can cause a lot of connection issues and undoing the operations is not possible.
DrTCP’s settings are bundled in one single window and they include path MTU discovery, Black Hole Detection, Time Stamping, Selective Acks and adapter options. After you’ve configured all of these, it suffices to press the ‘Save’ button. A reboot or a network restart might be necessary in order for the changes to take effect.
In conclusion, DrTCP is a handy solution for slow Internet connections, but it should be used with the utmost care. A registry backup is highly recommended before you perform any actions with it.