I want to open programs such as word or excel which are pretty much default for windows users, but don't want to be restricted to the specific file location.
For e.g. instead of

rt.exec("C:\\Program Files\\Microsoft Office\\Office10\\POWERPNT.exe")

is there a way of linking to powerpoint such that on a computer with a different folder for powerpoint it still works...

Not really an easy task
You can scan the directory structure until you find what you want but this solution is not really elegant.