XAMPP is an easy to install Apache distribution containing MySQL, PHP and Perl. XAMPP is really very easy to install and to use - just download, extract and start.
I actually do not think that XAMPP is really necessary on a Linux-system. Sure, on Windows it can make installation easier, but on Linux it's really just installing the right packages from your distro's packaging-system and that's more or less it.
Also that way it'll be sure you'll have no libraries in two different versions and all that.
Also I don't really like what I heard to be the default settings for XAMPP, they tolerate too much which, with new users, might lead to scripts that not are very interoperable.
Overall I think XAMPP is not a bad thing to make the setup of a development-environment on Windows easier, but it's far away from what I'd consider recommendable.
I do not recommend using xampp anyways. I mean yes it is good for starters and probably makes a great template but for those who do not wish to provide everything to the world then it is useless and chore to maintain and maybe even a security risk depending upon the skill level.
I do recommend the Cherokee Project