I'm Trying to upgrade from Mac OS X 10.5 to Mac OS X 10.6, but my imac won't let me... and yes it's intel based

Hello, what exactly happens when you try?

Os it a Retail Install Disc, or did it come with a different Mac?

Fo you have enough RAM & Free space?

Snow Leopard/10.6.x Requirements...

General requirements

* Mac computer with an Intel processor

* 1GB of memory (I say 4GB at least, more if you can afford it)

* 5GB of available disk space (I say 30GB at least)

* DVD drive for installation

* Some features require a compatible Internet service provider; fees may apply.

* Some features require Apple’s MobileMe service; fees and terms apply.