Catfan, please explain what you mean by "running slow". In what way?
Is it slow starting up and/or closing down?
Is surfing the internet slow? (if so what sort of ISP connecton do you have?).
Is it slow opening programs? If so, what programs?
Is it slow in other ways, eg playing music or videos?
Goto Start > Run and type in "msconfig", (without the quotes). Click OK and in the SYstem Configuration Utility click the Startup tab and look at the programs that load on startup. Some of them you may not need, and can remove the tick to stop them loading. If you need the programs later you can find them in your Start menu. If you do remove any startup items you will be prompted to restart your computer and on restart, you will get a message stating you are on selective startup. You can suppress that message in the message box if you wish.
Then look at the services that are running in the background. Right click the Taskbar, and select Task Manager. In the Processes tab see what processes are running in the background. Go here;
for more information on each process. You can end the process in Task Manager, or goto Start > Run, type in "services.msc", choose the Extended tab, highlight the service you want to stop, then right click it, select Properties and change the "Startup type" option.
See if any of that helps.