With Logic, it's all about RAM, hard drive, and processor. Stock laptop hard drives are relatively slow, so an SSD will help you and may be the best upgrade for a small amount of money, because Logic needs to write to disk as quickly as possible, the more tracks you are recording at once. But honestly unless you're not using many plugins, your 2GHZ processor is going to become a serious bottleneck. An SSD that you can migrate to your next laptop is worthwhile, but I would hold off buying more RAM and instead put the money toward a newer machine.
Unfortunately a program like Logic always has the capacity to max out any computer -- just and more tracks and plugins, and you'll eventually hit the ceiling. I have a quad-core Mac Pro with 12GB and 7200RPM drives, and even with that I have resource issues, so I've always found laptops way too limiting. If you don't need portability, you mind find a newer iMac to be more capable. Also, one trick is to record plugin-heavy tracks to disk so the computer simply has to play the track, and no longer has to process its plugins.
If it's unclear what the bottleneck is, you can download the iStat Pro dashboard widget and view it while you're using Logic in order to see what resource is maxing out.