MS Paint and output resolution

[Grinder]

My apologies if the answer to my question is readily available on a FAQ
somewhere -- I've not been able to find anything from my searches at google
and google groups.

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I recently drew a simple pattern using MS Paint. I set the document size to
be 7" x 9", and by measuring the pixels in the document, have surmised that
it assumes 96 dpi vertically and horizontally.

Everything is fine on the screen, but I have problems with the output. A 2"
x 2" square will become 1 7/8" wide and 1 3/4" tall. The scaling is not so
bad, but I need to preserve aspect ratio more precisely.

Printing the same document with Adobe Photoshop yields a square that is
exactly 2" x 2".

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I'm using Windows 2000, but need to insure that this work on Windows 98 and
XP as well. Thanks for your time and consideration.