Screen DPI

[Peter T. Evensen]

What is the screen DPI.  I know on Mac, it is usually 72.  I'm wanting to 
create a pseudo-WYSIWYG card editor that lets you specify a size, like 3 x 
5, and it displays an appropriately sized card for one to place text 
on.   72 on Windows seems a bit small.  I was just wondering if anyone had 
a rule of thumb they used.

Thanks!

Peter T. Evensen
http://www.PetersRoadToHealth.com
314-629-5248 or 888-628-4588