For most people, its not really worth upgrading from a 1600+ to a 2400+, but it really depends on what you use your computer for. If you primarily surf the net and play games, then your windows will open 3 nano seconds faster, and you might see your framerate go up a bit, but you probably won't notice either. In this case, you would be better off selling your gF4 and buying a 9700 or saving up for a NV30. However, if you do a lot of CPU-intensive tasks, such as heavy duty Photoshop filters, MPEG decoding/encoding, 3D SMax, etc, then you should definitely notice the difference. I might suggest that you start by just overclocking your CPU. Most 1600+s will do 1.8GHz (2200+). With the increased bandwidth, your performance will be pretty close to that of a 2400+. I'm thinking that most likely, a Barton or Hammer would be the next "noticable" CPU upgrade for you.