SSD for sure. A 64 or 128GB drive, and keep the rest in the bank. Then upgrade the GPU when you really can't play the latest games anymore. Maybe even hold out till the next console generation hits + half a year for the GPU prices to drop accordingly.
dont think its worth to invest into the cpu, only for powersaving, but not for perf, while not the latest game: http://www.pcgameshardware.de/screenshots/original/2010/03/BC2-CPUs-1680.png SSD will probably help most with everyday tasks, a new graphics card could also help for fancy gaming, I would wait for a Nvidia…