Try the free beta release of Windows 8...seriously! http://windows.microsoft.com/en-US/windows-8/download. I did this with a pretty old PC that had been running XP. Once you get the hang of the new interface it is very fast and dependable. Everything worked great for me. Call MS support and tell them about your office 2007 situation. They should be able to help you download the program and get you your product key based on your registration info.
All the info they need is all saved on the hard drive. lol