I doubt your motherboard will support it so you'll have to consider the purchase of a new motherboard for a new cpu. If you find the performance worth enough, then yeah.
It depends, what do you do more, play games or do other stuff? If it is just games, I would recommend waiting and getting a DX10 card. If it is a lot of media related stuff (especially music and video encoding) go with the Conroe.
Or... you could just wait till the faster Conroes, or even Quadcore come out, your processor is very capable as it is. I am still making do with a 2.4 Ghz single core P4, but I am definately going for Conroe as my CPU is not nearly as nice as yours.