I believe that you may be looking for support from the wrong group. In this forum, it's ALWAYS time to upgrade!
Seriously... Socket-939 is here. PCI-Express is here. Dual core processors are here. SM3 video cards are here. What are you waiting for? Socket-M2 & DDR2? 65nm?
However, if your games play okay with what you have, you will almost always save money by waiting to upgrade.