I work quite a few years with XAMPP, and I always discovered some problems. Apache doesn't start because it's busy, PHP version is long time outdated, etc.
A few months ago I discovered EasyPHP
http://www.easyphp.org/ and the more I work with it, the more I like it. Smaller, quicker, more stable, latest PHP versions.
It can be used for Portable versions, too. Just give it a try, if you aren't that satisfied with XAMPP.