Thank you very much Ghostdust for your guide, i was able to install 10.6.3 and upgrade to 10.6.4 via Software Update, just one problem though: can't get the dreaded soundcard to work. Tried the AppleHDA with no success, i will search through the forums some more, if it doesn't work i'll try the iAtkos 10.6.4 distro.
BTW, after updating, the kexts in /Extra didn't load so i had to use Kext Utility, maybe this helps somebody