You don't need more memory or better grapic, however a ssd has a dispel loadtime effect. Buy 2x128 and run them in raid 0.
That's so over kill. Modern SSDs are like 2-5x the speed of HDDs. Raiding them is a total waste of money. They are way too expensive atm. In fact, you aren't going to see much of a performance diff in apps using them in raid. You best bet is to get one, load your games and OS on it, and use a regular HDD for storing music, video, and basic apps. SSDs will increase performance and reduce load hitching while playing games. in some cases you might even see 1-2 FPS differences, but for the most part, they just smooth everything out load times and general OS lag due to slow loading.
I opted to wait for the next wave of them before I upgrade. They are increasing in speed very rapidly, and the prices are almost at a good point. When I can get a performance 256MB SSD for sub 200, I'll be biting. ;P