If you look at those benchmarks, you will see that the performance of the Athlon64 4000+ is close to that of the Pentium4 Extreme Edition 3.73GHz. Over the range of benchmarks, sometimes the Athlon is fastest, sometimes the Pentium. Whatever, it is way ahead of your Pentium 4 2.8E, running at its stock speed.
thank u for all this but the dual cores arent as good at gaming, and an intel core duo e6300 costs 200 bucks and the good motherboards cost like 250 bucks, i only got like enoung to buy a case 100 the 4000 140 and a mobo 90
aren't quite as good at some games, but since most games are GPU dependent rather than CPU it won't make much difference whether your dual or single. However, your normal applications will prefer dual.
New games are likely to be written to take advantage of dual core and quad core CPUs, so spending money on single core processors is a slight backward step. However, if you're a keen overclocker with a good cooling system, then opterons are reported as being the business.