My name is Nibs... not dude... different generation. Thanks!
You don't "adjust" the ei.cfg file, you delete it completely.
Don't use your scratched up original disc, just download the Pro x64 ISO and then tweak it as the tutorial mentions.
I have done it both ways and there is no difference at all, either during install or after except for the options listed at the beginning of the install.
I have clients that I do installs and repair work for so having a disc like that is very handy, especially when a two year old boy decides the install disc is a pretty shiny little Frisbee thing!
As long as you have a Genuine Windows 7 Product Activation Key you'll be fine for the Ultimate x64 install.
Just do each step as listed and take your time, don't rush it.