X2 5000, would hardly make any noticeable difference I yet feel additional ram would be more beneficial. A cleanup should help a lot. 32-40GB should be ok, for anyone who don't install a lot of games. But do have a look at the reviews the Intel 40gb SSD's are significantly slower, as suggested earlier check if you can source an SSD with the Sandforce 1200 controller.
If you want to upgrade, I always suggest a platform upgrade rather than individual components upgrade. X2 5000 for eg. would be a 700mhz clock speed bump. Apart from games you will not be able to measure any performance difference (in games too, the effect will be negligible). But I suppose you have spent enough time evaluating options. In computer hardware purchase, waiting for a technology improvement is never fruitful, as there will be something better in future always.