Help with my PC, Buyin one

[Arctic]

Ive been shoping some sites, I came up with this, Its affordable ( I know knothing about building a computer so that really out of the question,   Feedback please, will this system with the motherboard have good room to grow,
I have a sound card and a ATI xl800 256 mg card now till I can affrod the Duel 7800 ,

And i have a quetion, Is the Duel core the way to go or should i get a 3.8 Ghz single pross w/ HT

CAS: X-BLADE Mid-Tower 450W W/ WINDOW & LCD Temperature Display + FAN CONTROL (GREEN COLOR)
CASUPGRADE: 12" COLD CATHODE NEON LIGHT [+10] (GREEN COLOR)
CD: (Special Price) LG GWA-4161 16X DVD±R/±RW + CD-R/RW DRIVE DUAL LAYER (GREEN COLOR [+9])
CD2: NONE
CPU: (Sckt775)Intel® Pentium® D 920 Dual-Core CPU @ 2.8GHz 800FSB 2x2MB Cache 64-Bit [+76]
CABLE: None
FLASHMEDIA: None
FREEGAME1: NEW !!! Free "World of Warcraft" for Any Intel PC/Notebook System
FREEGAME2: NEW !!! Free "City of Villains" with any Intel Pentium D Dual-Core PC System ONLY (Comes with Logitech Premium Stereo Headset)
FAN: INTEL LGA775 CERTIFIED CPU FAN & HEATSINK
FLOPPY: 1.44 MB FLOPPY DRIVE (GREEN COLOR [+7])
HDD: 160GB SATA-II 3.0Gb/s 8M Cache 7200RPM Hard Drive [+24]
HDD2: NONE
IEEE_CARD: NONE
KEYBOARD: PS2 MULTIMEDIA INTERNET CONTROL KEYBOARD (GREEN COLOR [+3])
MOUSE: PS2 INTERNET MOUSE W/ WHEEL (GREEN COLOR)
MONITOR: NONE
MOTHERBOARD: MSI P4N SLI-FI nForce4 SLI Chipset LGA775 DDR2/667 SATA RAID Dual PCIE w/7.1Audio,GbLAN,IEEE1394&USB2 [+42]
MEMORY: 2GB (4x512MB) PC4200 DDR2 Dual Channel Memory [+155] (Corsair Value Select)
MODEM: NONE
NETWORK: ONBOARD 10/100 NETWORK CARD
OS: Microsoft® Windows® XP Professional X64 Edition [+135]
PRINTER: None
PRINTER_CABLE: None
PRO_WIRING: Professional Wiring for All WIRINGs Inside The System Chasis with High Performance Thermal Compound on CPU [+19]
POWERSUPPLY: STANDARD CASE POWER SUPPLY
RAID: NONE
RUSH: NO; READY TO SHIP IN 5~10 BUSINESS DAYS
SERVICE: STANDARD WARRANTY PLUS ONE-YEAR ONSITE SERVICE
SOUND: HIGH DEFINITION ON-BOARD 7.1 AUDIO
SPEAKERS: NONE [-5]
TEMP: NONE (AS SHOWN)
TVRC: None
UPS: None
USB: Build-in USB 2.0 Ports
USBHD: NONE
VIDEOCAMERA: NONE
VIDEO: NONE [-44]
VIDEO2: NONE
WIRELESSCARD: NONE
WIRELESSPOINT: NONE
ZIP: NONE
_PRICE: (+1070)
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