What happened when you tried to install the older version? Did you get an error message?

If you got a message saying that there was a version of LW still running, open Task Manager (ctrl/alt/del) & see whether there's a LW process running. If there is, end the process. Now try to reinstall.

How did you remove LW? If you removed via Add/Remove programs, that's the wrong way & can lead to problems. In that case, use your computer's search to look for all files & folders with limewire in the name & delete whatever you find. Restart your computer & then try to reinstall LW.