Do these cordless mice/trackballs work?

My CPU's on the floor--my keyboard's on a slide-out from under the desk--my monitor's suspended above the desk--will a cordless mouse/trackball work? Does the beam or whatever go through, say, a desk?

 

Most of them have a receiver you can put in line of sight of the mouse/trackball and it will work just fine

 

Thanks for the quick reply! The guy at Fry's electronics was very vague...as usual!

 

i use a logitec cordless optimouse,quite expensive£50.00
but well worth it.......smoother and it works downstairs(the p.c is upstairs).......the kids found that out