Ho Broto.
Why is it throwing a memory error? It shouldn't...mmmm interesting. First, reboot your computer, that should clear memory issues. When restarted, check the Xampp Control Panel, see if Xampp is actually loading at start up first. The Apache, MySQL at least should be showing green. If it isn't, click Start on whatever options you installed. When green, go to the config button for the server and open the httpd.conf file. Scroll down until you see a line that says something like:
Define SRVROOT "C:/xampp/apache"
ServerRoot "C:/xampp/apache"
Check that this is where the installation really is, it supposed to be here, not anywhere else. Xampp doesn't like it being somewhere else, loses itself too easily. Then look for the line:
Check to see if it is looking at the right port. Then scroll down some more and look for the line:
If that is what it is reading then try addressing it as localhost/moodle/ in your browser. The 80 is the port number that Apache uses to listen for HTTP web based requests and localhost is the name given your Apache server.
If you want to set it to the ip address of your local machine/server, then change the line to:
listen 192.168.237.134:80
This assumes that the above address is static, in which case you might want to address it as 192.168.237.254:80, it cannot be dynamically assigned by the router. Obviously, you will have to reset your machine's network settings and instruct the router to not assign this address. HowToGeek.com can help you there if you are not sure how to do this. You can, if you have access to VMWare or similar, set up a virtual machine of, say, 60GB, and install Xampp there, giving that VM a static IP. Do not put anything else on it, just the Xampp, the Moodle, the WordPress, the Mahara, or anything else using PHP and MySQL, and your own web pages, of course.
Also, I have found that the Apache Friends distro of Xampp is a little more stable, but if you want to do anything fancy in Apache, like virtual servers, then you're going to have a problem if you don't edit the httpd.conf and other configuration files through the Xampp Control Panel. One tiny edit can bring the whole thing down.
I have been required to reinstall is for another project I have to work on, but my recommendation is to avoid Xampp at any cost. Good luck.