i hear the train to machu picchu from cuzco stops in ollanta for about two hours... is that true? if so, is it better to take a bus or taxi to ollanta that morning and then jump on that train. or is it better to stay in the sacred valley before the trip to machu picchu. we were planning to do the sacred valley after we get back from machu picchu into cuzco.
any advise would be greatly appreciated.

No, the stop in Ollantaytambo is about 10 minutes. Go to Peru Rail's website and you can see the schedule.

www.perurail.com

Yup. Ten minutes. A short stay, but be prepared to buy. The locals will come up to the window of the train to sell things. We got two terrific hand-made dolls that way.

And ... a lot of people embark and disembark from the train in Ollanta since this is the start of the Inca Trail. Watch your things in all the commotion. People have had bags lifted without them realizing it until the train was on its way again. (I know this has happened in the Backpacker train, but I've never heard of it happening on the Vistadome service.)

Also ... on the trip back to Cusco, minivans frequenty meet the train when it stops in Poroy. From there to Cusco, it's a short 15 minutes by road, as opposed to another hour or so on the train. The minivan is an extra five soles (about $1.50) if I remember, but I thought well worth it. And the minivan drops you off on Cusco's Plaza de Armas. Anyway, ask the train conductor about it on the return trip.

that's correct. You get off in Poroy and catch one of the vans to the Plaza de Armas. Well worth paying 5 soles and able to get a dinner (Alpaca Steak) on a decent time