install laminate over old hardwood
 

Hi, I'm about to install laminate over an old hardwood floor (the old floor looks like crap, has way too many gaps and squeaks/creaks too much to refinish). How should I prep the old floor - do I need to sand it to make flat, use screws to get rid of the squeaks? Anything else I should do?

Or should I remove it and put down plywood?

My opinion?
 

I would remove the floor and put down plywood. This way you can also fix the squeaks where they occur, under the existing floor.:)
Usually it is the nails in the plywood which go into the framing lumber (joist) underneath a floor which cause the squeaks. I would screw the floor down and countersink the nails that stick up.
Also follow all manufacturers recommendations and you will do just fine.
Good luck.

Thanks, makes sense!