Macbook Pro (5.1 Model Late 2008) 16GB RAM upgrade

Your Macbook Pro supports only 8GB (15'') or 6GB (17'') of RAM.

Apple states that it's 4GB, but OWC continuously check the max. supported RAM.

See this list here.

While I agree with others here that an SSD will give your MacBook Pro a great speed boost, the problem with a 128GB SSD is that it's probably smaller in capacity than your currently installed hard disk. If that's the case and you'll need to have a hard disk in the optical bay as well, the SSD solution is less attractive if you need the optical drive.

The problem with storage solutions that are too small is that they become less effective (fast) as you fill them close to their capacity. This is true of both hard disks and SSDs.

So, best to ask the questions:

1. How big is my installed hard disk and how much of it am I using, how much more of it will I be using in the next year?

2. Do I need the optical drive built into my MacBook Pro or could I move my current hard disk into that bay with an adapter.

If you can fit your MacBook Pro's current installed stuff into 64GB (unlikely but possible) then a 128GB SSD might work out well, even without the use of a hard disk for additional storage.