Mandrake is ok, Suse is probably the easiest. It has a nice user interface, updates automaticlly, etc. BUT!
If you would have went with Centos all you have to do is this
yum update all
and it updates all packages for you. Want a package installed?
yum install package.
Bang, done. You get the right package everytime. The problem is when you want a package that isnt supported or you did your install wrong or you want a special package. Thats when you have to put your thinking cap on.
Here are 2 very useful resources you will need when dealing with rpms and libs'
http://rpmfind.net/
http://rpm.pbone.net
Unfortunatly I didnt find any php5 rpms for Mdk either but I did find this
http://altruistic.lbl.gov/mirrors/cento ... i386/RPMS/php-5.0.4-5.centos4.i386.rpm
not to beat a dead horse but