Speed Boost on a Budget.

So, basically, i have the Unibody 2009 Macbook. Its pretty average by todays standards. 2.26ghz dual core, 2gb or Ram, and 250gb HDD. Not amazing, I get constant lag, and programs often bounce tens of times before opening. Luckily I have about 3 months left on warranty, so I'm going to get the battery replaced, and the bottom too (the rubbery surface must be expanding from heat, causing air bubble things in the rubber). Whilst this is being done, im going to ask they put in some new hardware. Because im on a strict budget, i have to question every cent, pinch every penny, and justify every buck.
Heres the two Upgrades:

1. Samsung 820 128gb SSD - I know its fast, but, honestly, is it worth the downgrade in memory? and how much does an SSD actually speed up an older mac? The Airs are zippy, but that could also be the extra RAM, or newer processors.

2. More RAM - Im thinking 8 gb, just because i have a fair sized iTunes library which i don't like to close. What do you think, is the extra RAM actually worth it? Or will the SSD do? I can afford it, but, on a student budget, it would mean living on scraps for the next week.

What do you think? how much extra speed (and subsequently, longevity) will i get out of this machine with these fresh parts?

Also, Note on the smaller SSD: I just purchased a 256gb USB flash drive, so that should do it along with the 128 on the hard drive.