Problems with Office 2007

Question

Tried to install Office 2007 as an upgrade over 2003. Now I can't use either versions as everytime I try a windows installer pop appears and tells me it can't find installation source (I have discs, but can't get it to read from them)it is wanting "MAINSP2op.msp". I can uninstall office 2007 (which I've done), but I can't repair or remove office 2003 to start fresh. trying to reisntall service Pack 2 for Office 2003 also did not work and system restore does not remove all aspects of office 2007. I am at my wits end and would dearly love any help anyone can provide. I have Windows XP