[KarmaKiller]

Hi and Welcome to TechIMO.

I myself always build my own tower. YOU get to select each and every part, so you get exactly the PC you wanted, without sacrificing anything. If your wanting a nice Quad core system, I'd recommend this:

Newegg.com - Intel Core 2 Quad Q6600 Kentsfield 2.4GHz 2 x 4MB L2 Cache LGA 775 Quad-Core Processor - Processors - Desktops

Newegg.com - GIGABYTE GA-EP45-UD3LR LGA 775 Intel P45 ATX Intel Motherboard - Intel Motherboards

Newegg.com - G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel Kit Desktop Memory - Desktop Memory

Newegg.com - OCZ StealthXStream OCZ600SXS 600W ATX12V / EPS12V SLI Ready Active PFC Power Supply - Power Supplies

Newegg.com - Western Digital Caviar SE16 WD6400AAKS 640GB 7200 RPM 16MB Cache SATA 3.0Gb/s Hard Drive - Internal Hard Drives

Newegg.com - LG Black 22X (CAV) DVD+R 8X DVD+RW 16X DVD+R DL 22X (CAV) DVD-R 6X DVD-RW 12X DVD-RAM 16X DVD-ROM 48X CD-R 32X CD-RW 48X CD-ROM 2MB Cache SATA 22X DVD±R DVD Burner - CD / DVD Burners

Newegg.com - PNY VCG88GTS5XWB GeForce 8800GTS (G92) 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card - Desktop Graphics / Video Cards

Newegg.com - Rosewill TU-155-P Black 0.8mm SGCC Steel ATX Mid Tower Computer Case - Computer Cases
For a total of $693 or
Newegg.com - Rosewill Conqueror WBK Triple 120mm Fans Steel ATX Mid tower Computer Case with Side Panel - Computer Cases
for a total of $718. That's without shipping factored in, but a lot of the parts I linked to had free shipping.