A regular myth among users is that a slow computer is directly related to the CPU and RAM a system has, however that is not the case many of the times.
Quite sometime back I had written about several ways to speedup your computer by deleting temporary files and also a useful utility that will speedup the computer, hard drive and internet access.
In addition to that there are several more ways to speedup your computer, for example by using startup managers to speedup startups, disk defragmentation to speedup hard drive, temporary file deletion to free disk space and improve speed among other things.
The How to Wiki has created a list of 12 steps that will allow you to speedup your computer and the best part is everything can be done without spending a dime, either using inbuilt tools in Windows or freeware software.
So if you have a slow computer, before you upgrade your CPU or RAM, check out on How to speedup a slow computer.