AMD Athlon 64 4000+, Athlon 64 3800+, and Athlon 64 3700+: AMD also has a handful of single-core high-end CPUs: the Athlon 64 4000+, 3800+, and 3700+. All three run at 2.4GHz. But while the 4000+ and the 3700+ feature 1MB of L2 cache, the 3800+ has only 512KB. One key difference between the 3700+ and the other two is that the 3700+ uses an older 754-pin CPU socket instead of the newer Socket 939. This will make upgrading more difficult in the future, particularly if you want to switch to AMD's dual-core processors, which also use Socket 939.
All three of these CPUs offer better performance per dollar than the Intel CPUs above. The 4000+ costs $550, the 3800+ costs $390, and the 3700+ will set you back $350.
As with many of the single-core AMD and Intel CPUs, AMD processors tend to exhibit faster performance in gaming, while Intel processors are faster at office productivity applications.
For standard office computing, the 3800+ represents the greatest value in terms of price and performance of all the single-core CPUs discussed above. The P4 660's performance is remarkable, but if you're going to spend almost $700 on a CPU, you might as well spend a few hundred dollars more and get a truly powerful CPU such as the Athlon 64 FX-55.
AMD Processors: Athlon 64 X2 3800+, Athlon 64 3500+, Athlon 64 3200+, Athlon 64 3000+
Intel Processors: Pentium D 820, Pentium 4 551, Pentium 4 541, Pentium 4 531, Pentium 4 521