So I'm looking to get an SSD for my laptop, a Dell Studio 1558 (core i5 520m 4gb ram) and I'm not sure which one I should get. I've been looking at the Intel X25-M 80GB which costs around £130, and seems to be a good option, though considering i'd be using the current HDD in my laptop (500GB) as an external one, so I'm wondering whether I should get a 64/60 GB one (which cost around £90) and if so, which one I should get seeing as Intel's next step down would be 40gb which I feel would be too small.