240 GB would be the way I would go and is also my suggestion if your pocketbook can afford. Prolly get one for around 150 during xmass sales. Get a 1 TB hard drive also, or at least I would for the reason, photos, videos, music, etc. That is if your into that stuff or you could go smaller HD.
Myself, I put the most used (important) programs and OS on my SSD . Otherwise I put my other programs on the Hardrive. I also put my documents, photos, videos, etc on the hardrive and not on the SSD. I use a 120 GB SSD.
Guncrasher is right, set your budget, then read and explore ideas of your components with in mind your use of computer.
my half cent