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Dell has the Dell Vostro 400 Core 2 Quad 2.4GHz Desktop PC + 20" LCD for $599 with free shipping.
Final Price for this deal: $599 + Free Shipping

Description:
Intel® Core™2 Quad Proc Q6600 (2.40GHz,8MB L2Cache,1066FSB)
Genuine Windows® XP Home Edition
1 Year Basic Limited Warranty and 1 Year NBD On-Site Service
Dell 20 inch Widescreen E207WFP Analog Flat Panel Display
2GB Dual Channel DDR2 SDRAM 800MHz - 2DIMMs
Single Drive: 16X DVD-ROM Drive
250GB Serial ATA Hard Drive (7200RPM) w/DataBurst Cache™
128MB NVIDIA® GeForce® 8300GS
No Floppy Drive
No Modem Option
Integrated 7.1 Channel Audio