For the general procedure, see Manual:Moving a wiki
on the MediaWiki site. I recommend making a Project:Backup page on your wiki where you can edit the exact procedure you like to follow, using wikitext
markup with magic words
to automatically generate filenames for your backup files. (I could give examples of what I do, but I would rather not broadcast internal filepaths etc. to the whole world.) The general instructions in Manual:Moving a wiki should be enough to let you work out the specific steps you will need to follow for your computers, using the software you prefer. I like command lines myself, so I use Cygwin
to give me a Unix-like shell on Windows. Then I can use Unix/GNU/Linux commands such as find, zip, rsync, unzip, mysqldump, mysql, etc. to manipulate and transfer the wiki database and MediaWiki files. You can either copy and paste the commands from your Project:Backup page into your command line, or you can put them in scripts. If you like to use GUI methods to drag and drop files, that may be harder to automate.
If you manage to install XAMPP so it does not rely on a specific drive letter, you can probably copy the whole XAMPP directory tree from one computer to another (it worked for me once), or you can install it on a portable drive. See Wiki on a stick
for the general method (using different AMP stacks) on the MediaWiki site. I might write an instruction page on the MediaWiki site for using XAMPP to make a wiki on a stick when XAMPP 1.7.2 is out and stable, since that version should make it simple to install XAMPP in a portable way.
As for where you should ask this type of question, this forum focuses primarily on XAMPP but it seems to have some MediaWiki discussion floating around too. The MediaWiki site has a Project:Support desk
page you can use, and it gives links to other MediaWiki support sites. You can also read and search the MediaWiki site. See the Template:Google custom
I created on Wikipedia; the examples section
gives a Google custom search link for the MediaWiki site. There are lots of questions and answers you can search there. You can copy the Google custom template to your wiki and then make convenient search links for all the sites you use for reference. Google custom search is sometimes more effective than a site's own built-in search, or you can use both search methods to increase your odds of finding something.
Sorry about my slow response, I only recently created an account here and I'm still learning my way around.