Old Intel based Macs?

As apple said you need at least a Core 2 Duo so a Mac with a Core Duo processor won't be able to run Lion.

Developper previews can run on Core Duo macs. There will probably be just one file to modify (using Pacifist to open the installer) to allow installation on any Intel mac.

Casey01 said:

So I take it the older Intel based Macs (Intel Core Duo) won't be able to run Lion?

Click to expand...

Your processor is 32 bit. Even if there currently is a workaround in the DP, there's no guarantee that any workaround will be in the shipped version or that some upgrade of Lion won't break on hacked 32 bit systems.

And Apple will not be testing Lion on the 32bit Macs so there could be problems lurking. My suggestion? Stick with Snow Leopard or bite the bullet and get a new system.