I can't install iTunes because of Bonjour

I'm running Windows XP on a Dell E6400

Everytime I try to install iTunes, I get this message, "Older version of Bonjour cannot be removed, contact your technical support group". I've tried to reinstall Bonjour, but it says I already have one installed and that the current installation has been stopped. I've tried removing Bonjour from my program files, which hasn't helped. I've tried uninstalling/repairing from the control panel's add/remove programs but it asks me to insert a disk, which of course I don't have (or know of). When I do a search for Bonjour on my computer, all I get are the installation files I've downloaded from CNET. Any suggestions? I'd really love to use iTunes but haven't for many months now simply because of this silliness.