Please keep in mind that 840 Pros from Samsung are better than the EVOs because they use memory with more write cycles on them. You get the same performance with EVO but less longevity.
Agreed. Go with the 240 or 256 GB option. I've had an 80GB SSD for about two years, and it's a huge pain. Windows fits, and not much else. If you use your computer enough to warrant getting an SSD, odds are you have enough big programs to need the space, particularly if you have a lot of movies, music, or video games. You don't want to drop a few hundred bucks on one of these things and wind up putting all the programs that will benefit from it on your second disk.
Suggestion: vote for >240 GB SSDs. Speaking as the owner of a 120 GB SSD, I can confirm that these fill up very fast, particularly if you're a PC gamer. I don't even really have any games on here and my most frequently-used applications have nearly filled it up. Storage micromanagement is something you'll want to avoid wherever possible.