You would also need to upgrade your RAM, the 1.4 only requires PC1600 or PC2100 RAM, 200 or 266Mhz frequency. The 3000+ needs PC2700 or 333Mhz RAM. While you may be able to set the RAM frequency to a lower speed then the CPU Front Side Bus it will heavily affect performance. You should also have about 512MB of RAM.
Also the 2500+ is less then half the price of the 3000+ and would be a much more cost effective purchase; the performace difference would be minimal.