posix_tmpfile() needs to be reworked such that tmpfile() isn't used if 
MS_WINDOWS is defined, as it requires administrative privileges to run 
(it creates the file in the root directory) on Vista/2k8 (although 
there are reports of this not working on XP w/ 2.5: 
http://www.thescripts.com/forum/thread600423.html).

The recommended approach in MSDN is to use, quote, "tmpname or tempnam 
in conjunction with fopen": http://msdn2.microsoft.com/en-
us/library/x8x7sakw(VS.80).aspx

Assuming no one beats me to it, I'll look at creating a patch in the 
next day or two when I get some spare time.