Um... I guess you meant that you laptop has a 6 gigaBYTE hard drive with 1/3 taken by windows. As Mike and I said, go for a big hard drive (bigger ones on laptops may be expensive, but for desktops thay are cheap).

As Mike was saying, you don't need CPUs with speed of more than 1 gigahertz. It's pretty rare that you need that kind of CPU speed, so you are better off spending the money on memory and hard drive space.