Well the style of keyboard you are on now is QWERTY, see the top row of your keyboard if you don't know where that came from.

Back in the 1800's when typewriters first came out, people were getting too fast for the mechanical devices to keep up. The "hammers" that actually hit the page when you pressed a key were getting bound up and causing problems. SOOOO they made a new style of keyboard (QWERTY) to purposefully slow people down. It was made to FORCE you to type slower and more painfully.

They only planned on using this style untill they could make the typewriters able to handle the faster speeds. But it took them so long that more and more people got too used to the QWERTY style that they couldn't change them all back. It's stuck ever since.

So someone who is "alright" with Dvorak will usually be 10-30% faster than someone on Qwerty. Someone who is "great" can be upwards of 50-70% faster and 30-60% more accurate. It also has less hand movements so there's less repetative stress, most of the keys you use are on the homerow.