OSX 10.6 install problems

[ArranTurner]

Hi Guys,
a few months ago i was given a Late 2006 imac, i had to replace the hard drive and this all went smoothly, i attempted to install osx 10.6 as i had the retail disk but it told me i needed osx 10.5, i then hastily used the other disk i had presuming it would be osx 10.5 when infact it was 10.4.11, over the last few month i have been in a dilemma where i couldn't use my mac to its full potential because few programs work with 10.4.

I have the 10.6 retail disk but when i attempt to boot from it to perform a clean install (by holding the c button) it loads from the cd but i get an error saying that osx 10.6 can only be installed from 10.5 or click here to restore from a time machine back up.

I have read guides that take exactly the same steps as me when installing from osx tiger but on there computers it just installs fine.

I am using a windows keyboard but i believe this is irrelevant because it it loads the disc by holding 'c'

i also tried with a mac wired keyboard but that wouldn't even load the disk at startup.

Any help would be greatly appreciated as this is causing me a lot of hassle

regards Arran