ground connection on dedicated line?

Lewinski,

Using separate grounding rods is a violation of the National Electrical Code and also a great way to commit suicide.
If you can afford it, have the electrician use steel (NOT aluminum) BX armored cable (instead of Romex) and steel boxes, whichever way you decide to go. If you're having the outlets installed, running the 3 wire plus ground cable with isolated ground outlets can't possibly hurt, might help (esp. if you use the BX) and won't cost all that much more.
If you wish to discuss this further, you may e-mail me.

Lewinski,

Markphd is correct but his response might need clarification. Romex is one brand a type of insulated cable assembly generally containing, within its outer insulating sheath, 2 or 3 insulated conductors and an uninsulated ground conductor.
BX is a brand of steel or aluminum armored flexible conduit with insulated wires inside. In addition to protecting the conductors contained within, the armor serves as a ground conductor.
In the US, Romex and BX are used as generic terms, just like most of us call cellophane tape "Scotch tape" no matter what brand it is.

Lewinski,

I, too, vote "yes" on separate lines for analog and digital.

I recommend steel BX (rather than aluminum or copper) because only a ferrous material will block magnetic fields. You should not need the 18" spacing with steel BX (and as Tobias said, it's great for keeping the squirrels from snacking on your wires--copper is soft as well as pricey).