Trying to Update from PHP 4 to PHP 5

[TomKra]

I was trying to update my PHP 4.4.3 to PHP 5.1.6 on Suse 9.3 with PLESK 8.0.1 but Yast shows me a lot of package problems. I'm searching this Forum and the web without results. Has anyone a working solution for me.

TIA
Tom