Why doesn't this application file know I'm running Windows XP?

I had to replace my old hard drive and assumed that I had lost all my old files. I'm a computer dinosaur and still don't understand how everything works. However, I find a file in My Documents which I have been told is an application file. When I point at it with the pointer, it says Windows Office 2010, which I was using before the old hard drive died. The problem is, when I try to open it, I first get a message saying it's extracting the files and then I get a message saying this requires XP or later version. Windows XP is all I've ever run on this computer, and it was reinstalled after the new hard drive was put in. How do I get the file to recognize that I'm running XP? Also, a lot of times I get the message Windows Installer. Does this have anything to do with it? None of my recent files has a problem like this. Please help. Thanks.