I just checked it out. I have to say for once I will not take your advice. XAMPP seems to me to be a much more mature project. From what I see Uniform server supports PHP 5.2.3 xampp has 5.2.5 and php.net released 5.2.6 May 1st 2008.
In XAMPP I can switch between the php4.X version and 5.X version to test compatibility using only the admin interface. I see no metion of this on uniform server. Plus there is a Linux, Mac OS X, and solaris(still new) version in addition to windows. Uniform server seems to have windows and starting to gear up a Linux distro. Uniform server seems to be one guy, while apache friends seems to be a decent size team.
Looking at a few of the pieces, I think for now I will stick with xampp.
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