Which one? Same price, Velocity has the SLI upgrade option and liquid cooling, Hp has the more memory and larger case. Need professional opinions. HP Pavilion Elite d5200t ATX customizable Desktop PC EPP_HP_NE504AV#ABA – Genuine Windows Vista Home Premium with Service Pack 1 (64-bit) – Intel(R) Core(TM) 2 Quad processor Q9550 [2.83GHz] – SAVE $40! 8GB DDR2-800MHz dual channel SDRAM [4x2048] – 500GB 7200 rpm SATA 3Gb/s hard drive – 512MB ATI Radeon HD 4650 [DVI, VGA, HDMI] – LightScribe 16X max. DVD+/-R/RW SuperMulti drive – LAN port on system board (10/100/1000Base-T), no wireless LAN – 15-in-1 memory card reader, 2 USB, 1394, audio – No TV Tuner w/remote control – Creative Sound Blaster X-Fi Titanium – No speakers – HP keyboard and HP optical mouse – Microsoft(R) Works 9.0 – Norton Internet Security(TM) 2009 - 15 month – HP Home & Home Office Store in-box envelope OR General Spec Brand Velocity Micro Model E2250 Recommended Usage Gaming Processor Intel Core 2 Quad Q9450(2.66GHz) Processor Main Features 64 bit Quad-Core Processor Cache Per Processor 12MB L2 Cache Memory 4GB DDR2-800 Hard Drive 750GB 7200rpm SATA Optical Drive 1 Double-layer DVD±RW/CD-RW Optical Drive 2 DVD/CD-RW Combo Graphics NVIDIA GeForce 9800 GTX 512MB Audio Intel High-Definition Operating System Windows Vista Home Premium 64-bit CPU CPU Type Core 2 Quad Installed Qty 1 CPU FSB 1333MHz CPU Speed Q9450(2.66GHz) L2 Cache Per CPU 12MB CPU Socket Type LGA 775 CPU Main Features 64 bit Quad-Core Processor Graphics GPU/VPU Type NVIDIA GeForce 9800 GTX Graphics Interface PCI Express x16 Memory Memory Capacity 4GB DDR2 Memory Speed DDR2 800 Maximum Memory Supported 8GB Hard Drive HD Capacity 750GB HD Interface SATA HD RPM 7200rpm Optical Drive Optical Drive Type DVD±RW Optical Drive Spec Double-layer DVD±RW/CD-RW Optical Drive 2 Optical Drive 2 Type DVD/CD-RW Combo Audio Audio Chipset Integrated Communications LAN Chipset Integrated Front Panel Ports Front USB 2 Front IEEE 1394 1 Card Reader Digital Media Reader Back Panel Ports COM 1 LPT 1 Rear USB 4 Rear IEEE 1394 1 Expansion PCI Slots (Available/Total) (2/2) PCI (2/2) PCI-E x1 (1/2) PCI-E x16 Both processor have 12MB cache, but the Velocity is 2.6ghz and a Intel 9450, Hp is 9550 2.8ghz.