For Web-dev, can the PHP Processor be installed on a regular Windows XP machine, such that viewing PHP files through a browser executes the PHP script? (NOT Windows Serv
You can, as already mentioned, go about it the easier way by installing something like XAMPP (my personal favorite) or, if you want to mimic something closer to a server environment, install VirtualBox/VirtualPC and create a virtual machine running Debian or whatever server OS you need, with the appropriate PHP, Apache2 (etc...) packages.
I find this to be sometimes preferable to using XAMPP, since XAMPP comes packaged with a specific set of Apache or PHP modules and you may need something not already pre-packaged with XAMPP.