I'm on Debian and the latest ImageMagick is 4.28 (even in Woody!)
It doesn't matter what Linux distribution you run, there are Linux binaries (gzipped tar) of recent ImageMagick (5.2.x) on the ImageMagick ftp mirror sites. Just configure the install script and run it. It'll write over the binaries of your crusty old Debian-provided ImageMagick and your system will never know the difference. I upgraded my Red Hat system the same way and I didn't void the warranty. 😉
