As of 2001 it is no longer possible to hike the Inca Trail without a guide. All travelers should go through an authorized travel agency to hike the Inca Trail to Machu Picchu. It is up to you to decide whether you want to pack your personal belongings or hire a porter. A travel agency that treated us very well was Llama Path.
Agencies will handle major meals along the trip and will carry tents and bed rolls for you regardless of if you bring your own; just plan to use theirs. Our porters offered to carry up to 16 kilograms of personal belongings for $190USD, or 8 kg @ $95USD. You may upgrade your porter along the route if necessary, be sure to bring cash if you think you may need to take advantage of this.
For more information on what to pack, take a look at my post: What to pack for the Inca Trail.
