Upgrading my Mac: Will it increase performance?
I always recommend an SSD as an upgrade to revitalize just about any system. You will notice a performance increase with an SSD, though it will be mostly load times (we're talking a night and day difference here). You aren't going to increase your frame rate. Sure, it's true that your system doesn't have many more years (months) left in it, but if you buy a good SSD you can move it to your next system.

8GB of RAM isn't too expensive, so it really depends on how long you want to keep the system. Any performance boost you notice may or may not be your imagination.

If it were me, I'd do both because I do like to squeeze the last bit of life out of my electronics (though I would have done these upgrades a few years ago) and if it is generally working for your basic needs why get a new laptop?