Another alternative, if you need large amounts of space, is to go with the Seagate Momentus XT 750GB hybrid disk. It has an 8GB SLC chip (basically an SSD) on board, and caches your most common reads. So, you get some of the SSD performance boost, but still have 750GB's of storage space. I think it runs around $150 on Amazon.
Samsung 800 series is currently the best SSD out there.
The Samsung is the best for access time, voltage uses (very low) and is being used by Apple on their Retina MB Pro.
Another SSD drive to consider is by Crucial and Corsair.
I'd like to recommend OCZ but their SSD drive, has issues with some MB's.
If you're in a budget, consider JWS1982 suggestion of going with a Hybrid Drive which is the Seagate Momentus XT 750. Steer clear of the 500GB version of the Momentus. Some MB have issues with them.