GUYS.
Let me address some of the questions asked in this thread.
"Is this free money?"
No. If you just mine with your computer, you'll receive bitcoins at a SLUGGISH pace. You might make a couple dollars in a week if you're lucky.
"How does it work?
This is how it works - everyone who's mining at the same time are working on decrypting a chain of "blocks." The one person who decrypts the block gets like 25 bitcoins. However, it's so rare that it's basically useless to mine solo.
"Why would I pool mine lol"
When you join a pool, you join up with hundreds of people mining at the same time. When one person in the pool receives a block, EVERYONE in the pool gets a piece of it evenly. This creates a more steady, stable income in BTC.
"What hardware do I need?"
If you absolutely must mine on your computer, don't use your CPU. Always GPU mine because it's much faster - GPUs contain hundreds of microcores (I think that's what they're called) and thus are much more efficient.
Many people build rigs which are composed of many GPUs chained onto several motherboards, all running on some management software so you can control all the rigs at once. This makes a crazy amount of money, but what's been happening recently is that companies like Butterfly Labs have been releasing ASIC machines, which are machines BUILT for cryptography. However, they're WAY out of stock and it's taking forever for people to get their machines.
Some people believe that ASIC machines will be the end of GPU mining.