Power Mac G4 to G5 question

Hi guys, i have a G4 on my studio since many years now i bought a G5 dualcore, the question is if i just put the harddisk from the g4 into g5 what happen? It works? or it doesn't?

I know is better to format and restart everything, but i have many to reinstall and search for codecs, application, vst etc..

Exist something like "True Image" for OSX?

thanks in advance.

I suggest that you backup your 'Applications' folder into a Disk image (.dmg) and then restore contents back on your new mac. Use DiskUtil to create a blank disk image.

Also, I suggest you backup your user home folder incl. ~/Library/Preferences for your settings.

mhh inever tried, if something happen i'll lose many data.
I wait for get some other information before act.

do has somebody any other suggestion?