i own that exact macbook,
i've read that it can run up to 8 gb of ram without problems and an SSD would be the best option for an hd upgrade.
i was looking after that, but i didn't understand which kind of SATA compliance would be more appropriate.
also i wonder if the 2.0 ghz processor would become a bottleneck after those upgrades.
thanks for any answer
Maximum Memory 8.0 GB (Actual) 4.0 GB (Apple) Memory Slots 2 - 204-pin PC3-8500 (1066 MHz) DDR3 SO-DIMM
SATA II - 3.0 Gb/s interface controller.
The CPU speed is adequate. The GPU is a 9400M that has been problematic in some models. This was due to a faulty batch of chips from Nvidia. Apple had a replacement program: MacBook Pro: Distorted video or no video issues.
I upgraded my 2009 MBP with a 256GB Samsung SSD and I cannot begin to describe the impact. It was like getting a new computer. I doubled the RAM - to 8GB - a few months later and that gave it another boost. Just to give you an idea - I have a top end 2013 iMac with a Fusion drive and my MBP doesn't feel slow in comparison - it would have before the upgrades. Your 2008 isn't that much different from mine so you should feel a similar impact with a lot less impact to the wallet.
BTW at the shop where I work part time the three favorite drives among the techs are Samsung (for the price and quality) with Crucial and OWC tied (for speed and quality).