How to delete old version of firefox on iMac

I have an older iMac 20" running lepoard OS and have just downloaded the new Mozilla Firefox version 3.5.7 It works fine (except that the new bookmarks section is very confusing and non user friendly) but I cannot get rid of the old version of Firefox 2.0.0.4 I have looked everywhere in my hard drive and all my application folders and can't find it anywhere. I have put it into trash many times and it always appears when I power on. I have tried putting it in appledelete and that doesn't work either. It automatically logs on to the old version which I have to shut down, then I open the new version and it works fine. How do I get rid of this old version? Thanking you in advance.

Have you tried moving Application Support in Library? See Removing Firefox 2 from this link and check it is not in the startup or login items:-

Mozilla Firefox 2 Release Notes

Thanks Harryb I found a Firefox file in my Profiler folder, trashed it and now it's gone. I only have the new version Horray!!!! Thanks again.