iMac - Polycarbonate intel core 2 duo

After reformatting an imac polycarbonate intel core 2 duo to OS X 10.4, i am now trying to put 10.6 on it, it is a legit DVD, but when rebooting it to install mode it claims the software can't be installed on this computer, how can I overcome this and why would it say this, i have had a look at the specs for 10.6 and it has an intel core 2 duo, enough ram and space, why would it say this if i meet the spec?

Is this "legit DVD" gray colored? If so...the gray disks are model specific & can only be used with the model Mac they shipped with.

- Nick

Ahh i believe it is, i had a feeling it would be something like that, what disc should i be looking for then, that isn't model specific

A retail version of Snow Leopard. Available at your local Apple store or Best Buy. The upgrade is $29, the full boxed set $129.

I think you need to buy the boxed set when upgrading from tiger to snow leopard