Opinions on CPU's below as to the best performance-wise.
AMD Duron - Socket A $ Inc GST
AMD Duron 1.4GHz, Socket A, 133MHz FSB (266MHz), 128k-L1 + 64k-L2 Cache, with Heatsink/Fan $95.00
AMD Duron 1.6GHz, Socket A, 133MHz FSB (266MHz), 128k-L1 + 64k-L2 Cache, with Heatsink/Fan $100.00
AMD Athlon "XP" - Socket A $ Inc GST
AMD Athlon XP2000+ (1.67GHz), Boxed Socket A, 133MHz FSB (266MHz), 128k-L1 + 256k-L2 Cache, with Heatsink/Fan $135.00
AMD Athlon XP2200+ (1.80GHz), Boxed Socket A, 133MHz FSB (266MHz), 128k-L1 + 256k-L2 Cache, with Heatsink/Fan $150.00
AMD Athlon XP2400+ (2.00GHz), Boxed Socket A, 133MHz FSB (266MHz), 128k-L1 + 256k-L2 Cache, with Heatsink/Fan $170.00
AMD Athlon XP2500+ (1.83GHz, Barton), Boxed Socket A, 166MHz FSB (333MHz), 128k-L1 + 512k-L2 Cache, with Heatsink/Fan
$185.00
AMD Athlon XP2600+ (1.917GHz, Barton), Boxed Socket A, 166MHz FSB (333MHz), 128k-L1 + 512k-L2 Cache, with Heatsink/Fan
$215.00
AMD Athlon XP2700+ (2.167GHz), Boxed Socket A, 166MHz FSB (333MHz), 128k-L1 + 256k-L2 Cache, with Heatsink/Fan $240.00
AMD Athlon XP2800+ (2.083GHz, Barton), Boxed Socket A, 166MHz FSB (333MHz), 128k-L1 + 512k-L2 Cache, with Heatsink/Fan
$300.00
AMD Athlon XP3000+ (2.167GHz, Barton), Boxed Socket A, 166MHz FSB (333MHz), 128k-L1 + 512k-L2 Cache, with Heatsink/Fan
$440.00
AMD Athlon XP3200+ (Barton), Boxed Socket A, 200MHz FSB (400MHz), 128k-L1 + 512k-L2 Cache, with Heatsink/Fan $665.00
AMD Athlon64 - Socket 754 $ Inc GST
AMD Athlon64 3200+ Socket754 CPU OEM (without Fan) $770.00
AMD Athlon64 3200+ Socket754 CPU Boxed $895.00
AMD Athlon64 FX51 & Opteron - Socket 940 $ Inc GST
Call $0.00
AMD Athlon "MP" - Dual Socket A $ Inc GST
Call $0.00
Intel Celeron - Socket 370 FC-PGA2 $ Inc GST
Intel Celeron 1.3GHz, Socket 370 (FC-PGA2) with Heatsink/Fan $130.00
Intel Celeron - Socket 478 $ Inc GST
Intel Celeron 2.0GHz CPU, Socket 478, 100MHz FSB, 128k L2 Cache with Heatsink/Fan $145.00
Intel Celeron 2.2GHz CPU, Socket 478, 100MHz FSB, 128k L2 Cache with Heatsink/Fan $150.00
Intel Celeron 2.4GHz CPU, Socket 478, 100MHz FSB, 128k L2 Cache with Heatsink/Fan $145.00
Intel Celeron 2.6GHz CPU, Socket 478, 100MHz FSB, 128k L2 Cache with Heatsink/Fan $195.00
Intel Pentium 4 - Socket 478 $ Inc GST
Intel Pentium 4 (Socket 47

2.66GHz (533MHz FSB) CPU & Heatsink/Fan $350.00
Intel Pentium 4 (Socket 47

2.6GHz (800MHz FSB), Hyperthreading CPU & Heatsink/Fan $350.00
Intel Pentium 4 (Socket 47

2.8GHz (800MHz FSB), Hyperthreading CPU & Heatsink/Fan $430.00
Intel Pentium 4 (Socket 47

3.0GHz (800MHz FSB), Hyperthreading CPU & Heatsink/Fan $530.00