If I remember right, the Samsung beats the Crucial. As for size, 256GB is adequate for most rigs, as long as you plan to store big media files/libraries on a HDD. However, if you have the money for a 512GB, do it. More is always better, with regards to storage space. Personally, I'd put all my software on the SSD, and use the HDD for storing just data files (music, movies, pictures, documents, etc.). As for the 7mm drive in a 9.5mm sled, you shouldn't have a problem. The mounting holes should be in the same spots (if they're not, you don't want the drive, it's not built to industry standards), the drive just isn't as tall. I just recently pulled a 7mm HDD that failed, and put a better 9.5mm drive in it's place (in a laptop, even more cramped, and used a drive sled). In case you're interested, here are some of my favorite benchmarking and review sites: [url=http://www.phoronix.com]Phoronix[/url] [url=http://www.smallnetbuilder.com]SmallNetBuilder[/url] [url=http://www.tomshardware.com]Tom's Hardware[/url] [url=http://www.cpubenchmark.net]CPU Benchmark[/url] That last one features a searchable list comparing hundreds of CPUs, GPUs, RAM, and other components. The data is submitted by users who run a benchmarking suite and upload the data to the site for comparison. It's one of my favorite sites to visit when I'm having a hard time making up my mind about specific components.