It doesn’t really matter about total GB available. It’s more or less about your processing speed and the amount of RAM you are running. Think of the RAM as short term memory and it serves as the function of your actions in correlation to your applications being used and processed. The more RAM the more you can function. I would recommend upgrading your laptop equipment every 3 years. In your case I think a simple RAM upgrade will do. It sounds like your CD/DVD is squished meaning too much pressure has been applied on both sides of the laptop and damaged the spinner inside or the actual CD/DVD reader. Furthermore it sounds like you need a new battery charger. I believe the charger is around 80 bucks, and I got 8GB worth of RAM from Frys Electronics for 60 bucks. I don’t know if your particular MacBookPro can even run 8GB of RAM. Check the “tech specs” of your MacBookPro to determine this. Take into account the year your model was produced as it will determine how much RAM you can do. Seeing that it is 4 years old and your DVD drive is bad, and perhaps your overall processor might not even be a Duo Core Processor you might want to consider just buying a new MacBookPro. That’s what I did, and I juiced it up with the upgrades. Good luck!