One of my main complaints with the commercial distributions is that the majority of them only release bug-fixes for older releases, they don't release, say, PHP 4.3.2 when the distro came with PHP 4.1.1. This is true of all of the RPM distros.
The way around that I found was to use
Debian. With the 'apt' util you can upgrade your entire system to the latest release using one command (apt-get dist-upgrade), update your installed software to the latest versions (apt-get upgrade), or just install one specific program (apt-get install progname). It keeps a local filelist of all of the available software from the various file sites, which is updated using another command (apt-get update), and you can change the list of sites you want by editing a text file (/etc/apt/sources.list). Finally, they tag specific program releases as either stable (stable as a rock), testing (generally stable as a rock) or unstable (tends to be quite stable), and you can set apt to only pick files from one branch by editing one file (/etc/apt/preferences).
Personally I use Debian Sid (the cutesy code-name for the unstable releases) and have done for several months, even with the KDE 3.2 CVS builds, without any problems that
I didn't cause.
To make things easier for beginners, there are several commercial distributions that are based on Debian -
Lindows,
Lycoris and
Libranet, along with the self-booting
Knoppix which makes a great emergency repair disc.
Damien