If you don't have a lot of computer experience Do Not attempt to install a kernel. If anything breaks, you could end up having to install again. That being said, you can of cause get a more fast computer by compiling your one kernel - but it is a mater of luck and experience, if it works.
If you want to download the latest source codes, try www.kernel.org
on its front page, you should be able to find the latest 1.6 kernel. (Be sure, it is the Full Source, not just a patch)