No Parallels after Archive & Install

My OS X (10.4.11) became a little quirky after three years so I reinstalled with an Archive and Install. Now I can't get into Parallels to start up my Windows XP virtual machine. I get the error message "Parallels Desktop is unable to operate properly since it cannot communicate with one of its drivers ... re-install Parallels Desktop." I have my original Parallels 3.0 installation CD so I suppose I can figure out how to do this. (My iMac was purchased with Parallels pre-installed.) Do I need to uninstall before i re-install? I have on my desktop the Parallels alias labeled "Microsoft Windows XP.pvs" plus I have in Applications an alias labeled "Parallels Desktop". If I need to uninstall, can I just drag these two to the trash? I am not adept at this sort of thing, so I need some guidance. Thanks.