Landing Canada & back to US

Hello There,

I plan to drive into Canada from Buffulo for landing and come back to USA within a week. I am trying to make clear several questions. Hope you can help. Many thanks in advance.

First of all, I am holding H-1B and my wife F-1 in USA. Some friends told me that when we enter Canada, we have to hand in our I-94 card, so we will not be able to come back USA unless we re-apply a new one. Even that they will not give us an H-1B visa within a short time.

Second, assuming we don't need to turn in our I-94 cards, will we have troubles to came back USA? Some say YES and others say NO. What might happen at the US custom?

Thanks you again for any inputs.

Le2le