There are two ways you can do to increase your internet speed in windows vista
Method 1
1. Open Internet Explorer.
2. Click on Tools and then select Internet Options.
3. Click on Advanced tab.
4. From the settings, scroll all the way to the bottom.
5. Check the box of Use SSL 2.0 (Secure Sockets Layer) and uncheck the box of Use TLS 1.0 (Transport Layer Security).
Method 2(This method might not work well.. try it):
By default, the TCP autotuning is enabled in Windows Vista. Many websites do not respond well with this feature. So these sites are loaded slowly.