two operating systems?

I'm trying to install Windows XP, I started out with my Dell loaded with Windows 98 then went to ME, from that to 2000. I think, not sure, but I think that windows 2000 did not load properly and I don't know where to find it to take it out of the darn system. Every other time I've gone through the process, no problem but now while tring to load XP says "cannot continue, detect more than one operating stystem", HELP please. I did try to reload windows 2000 to take it out that way, again, "detect two operating systems" I took out ME and tried that, still the same thing. Help Help Thanks

 

Reformat? then install XP and 2000 to another directory? Upgrading OS's seems like a bad idea to me
--Adam