Hi and no, you can't re-install Win 7.
The solutions it's easy. The .aim and .bat are extension for programs that isn't safe modify.
.bmp is an imagine file, so, you can open this imagen with Microsoft Office Picture Manager, or the program that you prefer.
For open the .bmp just do this:
Right click on the file, open with, look for the program that you want for open this files and select, chechk the box that say "always use this program to open this files" and select Ok.