You can only open .tax files with the Turbo Tax program for that year. The taxprinter website uses the same Turbo Tax programs. Don't know if they use Windows or Mac. Probably the Windows Desktop program.
Or you can try to get a free transcript from the IRS or pay for a copy.
See this IRS website for transcripts - http://www.irs.gov/Individuals/Get-Transcript
For a fee of $50 you can get a complete federal tax return to include copies of W-2's from the IRS by completing Form 4506 - http://www.irs.gov/pub/irs-pdf/f4506.pdf
See this IRS Tax Topic - http://www.irs.gov/taxtopics/tc159.html
