I've been a long time user of XAMPP and noticed some really bad problems with the newer versions.
1. include Paths are messed up in PHP. In one particular site, I have an include() that loads a file from a child directory that itself includes another file from in the includes directory: include('config.php'); in order to reference the file in 1.7.7 Win, I have to make it include('includes/config.php); Under older versions (1.7.3) and the linux version of 1.7.7, this works correctly without the path, but in the windows version of 1.7.7, it fails. (Tried on 2 different XP machines and Vista as well)
2. The php command eval() is no longer working correctly, instead, it is acting like echo.
Finally, and this isn't so much a bug as a WTH were you thinking...
3. New security concepts. Dump them. They aren't in the Linux versions and XAMPP isn't for production servers, it's for testing servers, blocking stuff from other machines in a person's local LAN isn't your job, the Linux version realizes this, but the windows version oversteps it's bounds by changing crucial parts of the central project and makes it harder for people to actually use the product.