I think if you insert and boot from the disk1 it will give you an option to upgrade in setup. Basically all it is going to do is upgrade the kernel, along with some other packages. I'm not exactly sure what the full advantages of installing FC4 from scratch would be. But I would imagine there are probably not very many. Besides, you can just install the packages you need off of the FC4 disks without having to do a reinstall. I'm running the FC4 test kernel (2.6.11-1.1177_FC4) on my FC3 installation just for the heck of it. Running fine so far