What can I do to speed up my Windows ME

My computer is running very slow. I have run McAfee virus scan and have no infected files. I have an external hard drive connected for photos and music. I have cleaned up the temporary files and defragmented. Should I reinstall my Windows ME or could this be a hardware problem? It freezes up often and takes a long time to perform tasks. It is a Dell 8100, 3 years old. Any help would be greatly appreciated.