We removed a housefull of 60's wallpaper and are now in the process of repairing, mudding, sanding the drywall. What's the best, fastest, most economical way to sand the drywall? Do the new power sander - vacuums work? Are they worth the money to rent? What is a reasonable amount of time to expect it to take to sand a room? One night? One week? Thanks for the input.