Installing OS X Lion on an iMac I have a new iMac where I need to install OS X Lion. The HDD is erased, but the newer iMacs don't come with bootable CDs. 

But I do have a MacBook Pro OS X lion CD. My question is whether can I install OS X using this CD rather than downloading the whole thing?
The OS X install disks that used to ship with new Macs were specific to those machines, and can't be used on different models. You're going to have to use Lion Recovery to re-download and install Lion, or go to an Apple Store, they can reinstall it for you if your internet connection isn't sufficient.

It's also likely that the install DVD for your MacBook Pro is for Snow Leopard, any machine that shipped with Lion didn't come with install media, just a recovery partition.