While it may have appeared to help your friend, it won't. While he may have gotten a fast download, it was not due to a processor upgrade.
Internet/download speed is limited by your connection speed, and internet traffic. Even if your internet connection is what most home users considered very fast, say 4-6meg per second, even a 14 year old 486 machine could handle that with ease.
Nothing you do, except upgrading to a faster internet connection will help.