From Irakli Nadareishvili's blog today, there's a new post that shows exactly how to get the PECL memcache client up and working with a default XAMPP installation in PHP4.
XAMPP is an absolutely wonderful, packaged, self-contained distribution of apache, mysql, php and tons of hard-to-install php extensions. [...] However, even with a long list of packaged extensions, obviously there may be a need to install an additional one. PECL Memcache client of memcached distributed cache server, is a very probable candidate for high-load systems.
Unfortunately, he notes, the default installation of XAMPP has a broken version of PECL installed and doesn't quite work like it should when new packages are installed. Thankfully, though, he found a workaround for the problem in the form of fourteen (well, really thirteen) easy steps involving things as simple as copying files, running a "make", and changing configuration settings to get things up and working.
He also includes a common error he had to figure out when making his install too - an issue where the installation might not be able to find the right libraries.