Today I installed a Samsung EVO 840 250GB SSD behind the optical drive and swapped out the original 1TB Seagate HDD for a 2TB one. Works great.
This is not a very difficult thing to do. Just keep calm.
The hardest thing was to put the motherboard back in place...
1. Read the steps a couple of times.
2. Have someone helping you holding the panel up while disconnecting those 4 cables.
3. Use a spudger and your fingernails to remove the cables. (spudger on one side/tab, fingernail on the other tab, or if possible just fingernails.
4. Mark every cable you disconnect (for example "pwr btw"). This make the rewiring a piece of cake.
5. Don't clean the "glass" with anything other than very hot water. I held it on the edges and held it in the shower. Any glass polisher or so will give you a headache. (I have tried to get it really clean several time before) Now its as good as new.
6. Yes. The fans WILL spin, but I use HDD fan control. Now it's super-SILENT ;)