From reading the other reviews, it appears that most people opt for the less time consuming option of going to Machu by train from Cusco.
I would, however, highly recommend you consider doing the 4 day trek to get there. Reaching Machu at 6am on the morning of the 4th day was one of the most incredible things i have experienced.
The trek itself is not all that difficult. if you are reasonably fit (if you can walk basically!) Granted, there are a few high passes (4200m is the highest) where you do get a bit breathless, but the views are astounding. Also, every day you get to see some other ruins, which are very impressive.
In terms of pricing, you will pay about $400. But if you look at what you get in the 4 days (everything basically!) it is money well spent.
We went in January 08 (the supposed rainy season) and were obviously very lucky with the weather as it rained once in 4 days. The company we used were based out of Cusco: United Mice. Highly recommended - good quality tents, good quality (and quantity!) of food and a highly knowledgeable and amusing peruvian guide.
I understand for some people time may be an issue, but if you can stretch to do it, you MUST do the trek. You will feel a great sense of awe and accomplishment when you reach the Sun gate early on the last morning and look down at an empty Machu Picchu...

You will need CASH (no credit cards accepted) to purchase your train tickets to Machu Picchu from Cusco, and the cost for the Vistadome is about $110 USD. At Machu Picchu, if you are not part of a tour you will need to purchase a ticket at the gate - and again, they DO NOT TAKE CREDIT CARDS OR USD!!! We were hit for a terrible exchange rate at The Santuary Lodge (but it was our only option)!

Wow... simply put, wow!

If you have the urge, even the slightest interest in visiting this wonder of the world (on the new 7 wonders list) don't hesitate for one instant. Machu Picchu may be the most amazing site I have every been to... more so than the Grand Canyon, more so than any Erupoean city, more so than the Norwegean or New Zealand Fjords.

Pictures do not do Machu Picchu justice... you must see it, feel it, to understand how spectacular this site is. To try and imagine the Incas not only living in but building the city in such a remote and seemingly uninhabitable place baffles the mind at times.

When we first arrived on top of the mountain, if was raining and we did get very wet (along with the other 500 or so tourists). But after a short drying off at the hotel (see my Sanctuary Lodge review) and some lunch, the skies cleared around 4:00pm and we headed back out... and to our pleasant surprise, there couldn't have been more than 150 people on the site. We nearly had the place to ourselves for an hour (it's bigger than you might think).

I am still in awe and would recommend that if you have the chance to visit Machu Picchu, don't pass on it. You will be amazed.

Machu Picchu is absolutely amazing. It's like nothing you've ever experienced, but there are some things that are very important to know
about before you head from Cusco (or where you may be) and up the mountain.

Getting there:
You really have only one option and that is the train. The rest either are grueling or take way too long for most vacationers. The train run by Peru Rail ([----]) is expensive. Even with the cheapest route, the backpackers train, it's still over $70! This isn't much by US standards, but when you pay only $30 for a nice room, it can hurt your pocketbook. We took the Vistadome 1, which is the first train out there. The seats are reserved and you do have a snack meal and beverage (for sale) cart. So, that's nice, but it's nothing spectacular. The backpackers is unreserved and on bench seats as opposed to individual seats. Either way is misery for 4 hours, but there really aren't other options. You'll spend just one hour doing painfully long switchbacks up the mountain in Cusco. It has amazing views but when you're looking at such a long trip anyway it's annoying.

Machu Picchu town (formerly Aguas Calientes)
This is very confusing because once you step off the train and out the door there are stalls upon stalls of goods that you have to find your way through and out the door. Most people follow each other, but no one really knows where they are going. When you reach a fork in the road and there's a bridge to your right and steps down in front of you, take the steps down and then cross over the bridge at the bottom and make a right up the hill for a few steps, on your left is the office where you will buy your ticket for the bus to go up to the entrance to Machu Picchu. Buy your ticket, but do not board at this point, because you have to purchase your entrance ticket, which is at the tourist center. You can ask anyone for directions (it's not that big of a town). The ticket to the entrance is about $40. Many guidebooks say that it's only $20, but that was prior to it being named one of the New Seven Wonders of the World. So, that's a big heads up for a proper budget. While in town you'll want to pick up some water and sandwiches there's only one cafeteria up there and it's
on the outside.

Then take the bus up the mountain. It takes about 30 minutes and is full of great views on either side because of the switch backs up the mountain to the entrance.

Machu Picchu:
Remember this is not an amusement park, there are no food or restrooms
inside, nor is it handicap or physically challenge-friendly. There are
a lot of steep stairs with no rails. Those with vertigo will feel extremely uncomfortable because of the slope of the mountain. There are wild llamas wondering around, which adds to the charm, but please don't try to pet them.

Even though Machu Picchu is at a lower altitude than Cusco, the air is still a bit thin, so keep in mind that you will have a little trouble breathing going up the large steps and you will tire faster than usual.
**Know your abilities. Don't attempt Waynu PIcchu unless you are very physically fit, and even then it's a challenge!***
You can hire a guide or take along a guide book and read it yourself, but some expertise is recommended to understand the full impact of the magnitude and culture.

What to bring:
Heads up, the weather is unpredictable so despite sun, you may have rain, despite clouds, you may have sun, so make sure to bring sunscreen (and apply ahead of being outside), bugspray and an umbrella. Sturdy walking shoes are a must and a backpack will give you better balance than an over the shoulder bag.

This is an absolute must do, you can do it in a day, but it's very, very tiring. On the other side of the coin, there's not much to do in Machu Picchu town, so the choice is yours, but if you do stay overnight, book as early as possible and confirm reservations frequently. I thought I had made a reservation and they never received the emails (or so they said) and so we were forced to do it in a day because of our schedule restraints.