MSIE has a habit of letting file name extension (.txt) take precedence before the server submitted content type (application/octet-stream)). This means that files ending with .txt always will be displayed. Another bug in MSIE is that it is extremely slow to display large text files (> 1 meg).
Is it possible to use mod_rewrite to fake a different filename (filename.dat) even if the original file still is filename.txt?