If you seriously think you might need to run an MS app,
do NOT format the hard drive. Install Linux in a separate partition instead. If you format the drive, you may have a hard time re-installing Windows, especially if all you have are OEM-specific installation media. Test your apps under WINE before you delete Windows. If they don't work, you can always boot Windows to run them. Unless you're in a pinch for hard drive space, don't delete Windows until you're positive you don't needed. It's much easier to leave it there than put it back.