You have no idea how much faster your PC will feel with an SSD. Windows boots up faster, programs load faster, everything just works faster. My laptop has an HDD and it frustrates me now how slow it is. Not all games load faster but save games, levels and area's load much faster, in some cases it's even instant.
Any decent quality SSD will outlast you and I don't mean just your use of it. There are different types using different components but even this cheap one of mine will last me 90 years at the rate I'm using it.
What's far more important than whether it'll end up in a museum in the future before it breaks, is which one you're looking at getting. I would recommend a Samsung 840 or 830 if you can get one, though I've heard good things about Crucial's M4 too, though they're more expensive.Here's the thread on the 830/840's.