This deal has ended.
Dell again has a powerhouse Dimension E521 for $644. It has the new AMD Athlon X2 Dual-Core processor, 1gb memory, 160gb hard drive, 16x DVD / CD burner, 256mb video card and a 17" LCD flat-panel monitor (it is $734 if you upgrade to a 19" UltraSharp LCD and $864 if you upgrade to a 20" Widescreen UltraSharp LCD). The price should be valid through 6am CST 10/19. Shipping is free.