An extenstion of this question:
https://stackoverflow.com/questions/50335/ok-cancel-or-cancel-ok
Where should the APPLY button go (clicking the APPLY button has the same effect as clicking OK, except the dialog remains open)?
Windows typically uses OK-CANCEL-APPLY, but my inclination is to use OK-APPLY-CANCEL.
Also, if the APPLY button is clicked, should the CANCEL button text be changed to CLOSE until another change is made in the dialog? I’m assuming the APPLY button will be disabled if there are no changes to apply.
I’d stick with Chris Roberts’ answer: be consistent with the operating system.
Edit: even if you consider the positioning wrong, keep in mind that in the case of Windows, Microsoft does a ton of user testing and focus-group goodness. Even if Ok-Cancel-Apply isn’t the best answer for your application, if the users are accustomed to that layout then it’s likely the least bad solution.
I think about the recent change to the Ubuntu UI where the Canonical team decided to move the minimize/maximize/close buttons at the top of the window chrome. The functionality wasn’t changed, but boy did it irk some users (myself included). Of all the problems your application may encounter, do you really need to add a UI headache like that?