Question About System Before Buying

Hello everyone, Im new to the forums so I dont know where to post this.

Im looking at

http://www.newegg.com/Product/Prod [...] 6883113099

Right now.

Im wondering if it will play these games at Ultra or High Settings [Mainly Ultra]

Keep in mind I will be replacing the Graphics card with a 4850HD One I have in my Old computer.
Also I dont know how to overclock.

Games Needed To Be Played On ULTRA:

World Of Warcraft The Lich King

Farcry 2

Assassins Creed

GTA IV

Games Needed To Be Played On High:

Crysis

Left 4 Dead

Fallout 3

Other Major Titles.

Can anyone let me know can these games be played well on this machine?

Thanks in advance.

P.s Specs located below for those of which who dont trust newegg links =D

General Spec
Brand Gateway
Model FX4200-EBF01A
Recommended Usage Gaming
Processor AMD Phenom X4 9750(2.4GHz)
Processor Main Features 64 bit Quad-Core Processor
Cache Per Processor 4 x 512KB L2 Cache
Memory 8GB DDR2 667
Hard Drive 1TB SATA II 7200RPM
Optical Drive 1 Blu-ray Disc / HD DVD Combo Player and Super Multi DVD±RW DL Drive
Graphics ATI Radeon HD 3850 with 1024MB Discrete Video Memory
Audio High Definition Audio
Ethernet 10/100/1000 Mbps Ethernet LAN
Keyboard Premium Multimedia Keyboard
Mouse USB Optical 2-Button Wheel Mouse
Operating System Windows Vista Home Premium 64-bit
Motherboard
Chipset AMD 780G
CPU
CPU Type Phenom X4
Installed Qty 1
CPU Speed 9750(2.4GHz)
L2 Cache Per CPU 4 x 512KB
L3 Cache Per CPU 2MB
CPU Socket Type AM2+
CPU Main Features 64 bit Quad-Core Processor
Graphics
GPU/VPU Type ATI Radeon HD 3850
Graphics Interface PCI Express x16
Memory
Memory Capacity 8GB DDR2
Memory Speed DDR2 667
Form Factor DIMM 240-pin
Memory Spec 2GB x 4
Memory Slots (Available/Total) 0/4
Hard Drive
HDD Capacity 1TB
HDD Interface SATA II
HDD RPM 7200rpm
Optical Drive
Optical Drive Type BD Combo
Optical Drive Spec Blu-ray Disc / HD DVD Combo Player and Super Multi DVD±RW DL Drive
Up to 8.5GB with Dual Layer Media
Write max: 16x DVD±R, 6x DVD-RW, 8x DVD+RW, 4x DVD±R DL, 5x DVD-RAM, 40x CD-R, 24x CD-RW
Read max: 6x Blu-ray, 3x HD DVD,16x DVD-ROM, 40x CD-ROM, 5x DVD-RAM
Audio
Audio Chipset Integrated
Audio Features High Definition Audio
Communications
LAN Chipset Integrated
LAN Speed 10/100/1000Mbps