Lots of things can slow down a PC including having too many fonts installed. First thing to do is go to Computer-Drive C - right click - go to properties - then to tools - click on defrag. This will take all of the many bits and peices of files and programs that have been stored scattered all over the drive and put them in order. This will take awhile to complete depending on the size of your hard drive - and it is best to leave the computer alone while it is doing this. This process will not harm your data. When it is finished then try some of the other suggestions here if it is still running slow.