His file has worked in 10.9, 10.9.1, and 10.9.2.
If you read the threads BEFORE you update you'll know what to expect.
It is approximately 1,000,000% easier if you have another Mac that can natively run Mavericks to create the drive.
Bare minimum video card would be a 2600XT Apple card. The 3870 will work if it has EFI but be aware that there is no OpenCl support, so things that would get help from OpenCl won't get that help.
I was amazed the first time I fired it up. Just about all of the other Macs from that far back are hopelessly stuck in the past, but the 2006 Mac Pro can still run current apps and OS.
A tricky part is that one of the boot.efi files is locked and so hard to replace.
There is a guy who has created an app that automagically copies the file everytime you shut down, this way you don't have to.
Making the installer work is a little trickier, hence it being easier if you have access to a 3,1 or later Mac Pro to create the drive.
Amazingly, even with the modded boot file, you will find that ti still works in 3,1 and later, making you wonder why they made it exclude the 1,1 to begin with.