When the Crucial M4 was relatively new, it was the to go to SSD. It wasn't the absolute fastest at the time, but it was easily the most reliable and priced fairly well.
Since then new drives have come out that have much better performance, very reliable and at a lower price point. So the Crucial M4 has largely faded away now, no reason to get it over newer drives like a Vertex 4 or Samsung 830.
Low Profile RAM is smaller, so it wont conflict with any CPU heatsinks.
Back in the day when you could only overclock using the FSB, you had to overclock the RAM in tandem with the CPU. As voltages rose to keep the memory stable and therefore clock higher on the CPU, it legitimately needed cooling, so massive heat-fins and waterblocks were useful.
Now that we can overclock the CPU separately from the RAM by using multipliers and the fact that DDR3 runs at lower voltages at stock, RAM doesn't need cooling anymore. The tall heat-fins are mainly for show, water-blocks are for those who have too much money, want to brag or are overclocking their RAM pretty hard.