Description:
The new version of the GIMP follows the Gnome style of placing the OK, Cancel,
and other buttons.  From what I can tell this style is a reversal of how Windows
does it:
For example, the the Gnome style is ordered as follows:
[Optional button] [Cancel] [OK]
However, all native windows applications are ordered as follows:
[OK] [Cancel] [Optional button]

Problems:
1) Basically, this can (and will) cause potential conflicts for windows users. 
People will be used to having the OK and Cancel buttons in other places and may
slip up by pressing the wrong button every now and then.
The reasoning behind this is based on how we think.  Once we learn a certain
behavior well enough, we can often do it without having to think about it in
much detail -- it becomes second nature to us so to speak.  With the OK/Cancel
button, this same thing applies.  The user becomes so accustomed to where the
button is that he will often click on the right spot without even reading the
words: it has become second nature to him.

2) Also, this idea of it being second nature to a person leads to another point.
 Switching the button order on Windows builds will cause some delay in using the
dialogs in GIMP.  Because the individual has to read the buttons more
throroughly and think through the process (instead of relying on second nature),
there is a slight delay in picking the right button.

BTW, I wanted to mention an example where I actually encountered these issues. 
At the time, I hadn't used the new version of the GIMP for very long (I still
haven't).  However, I did notice the change in the order of the buttons. 
Anyways, I had the "New Image" window open, and was gonna click the "OK" button
to create a new image.  However, instead of clicking the "OK" button, I found
myself clicking the "reset" button over and over again.  It had become such
second nature to me to have the OK button in that location, that even though I
had noticed the differences in the buttons earlier, I still was clicking the
other spot out of habit. Eventually I caught myself, and actually took some time
to look for the right button, but the overall process did end up taking more
time.  As this example illustrates, the location of buttons can become quite
ingrained, and changing their locations are likely to cause some disruptions
(and even dataloss) in some cases.

Proposal:
Thus, I basically propose that we used the Windows button order for Windows
builds of the GIMP.  From what I have seen, this means the reverse order of the
Gnome style.

I hope that this idea of separating things between Linux and Windows builds does
not deter this being done.  Perhaps it might be worth noting that the Firefox
project does this same thing of separating how Linux builds and Windows builds
handles the order of the buttons.  For the benefit of Windows users, I believe
it would be beneficial to do this in the GIMP, as well.