while you may be able to but the desktop apps for 2003 & 2004 on the web, they are likely the beta versions. the original program for that year issued by TT and would likely not reflect any law changes for those years. if you open the .tax file with these apps you could end up with a return that does not match what was filed.
it really depends on what you are looking for. because of structural changes TT needs to make to the app you may not be able to install them, "Taxprinter" is often a service that is mentioned that can provide you with a .pdf copy of the return as per the .tax file.
