Need help on buying a new graphic card!!

yeh but those are 500$ to 600$ cards, and on top of that i need a new desktop case thats another 150 becuase am planning to get an alienware case , and a new power supply thats close to 1000$, id rather build a computer, but to bad i dont really know about computers.... i just need a real good graphic card that runs games like Flight Simulator FSX, Crysis WarHead, Assasin Creed 2, Call of duty modern warfare 2 etc.. on ultra high graphics without lagging.. i might need to buy a processor if thats even possible

on second thought the ATI Radeon 5850 isnt so expensive... its either between Nividia GeForce GTX 285 or the ATI Radeon 5850, which would you perfer for gaming

Gaming requires a PC dedicated to gaming - and all the parts must work together properly - a quad may bottleneck a 4890 - unless you go for a Phenom X4 955.

well i decided that i rather buy a new desktop rather then doing all of this becuase am not so smart on computers, this is the desktop am gonna by.. please reply to if its the right one for gaming performance,

CHASSIS ColorCosmic Black, Alienware Aurora Chassis
PROCESSOR: Intel® Core™ i7 920 2.66GHz (8MB Cache) Quad Core Processor SYSTEM
Genuine Windows® 7 Home Premium, 64bit, English
VIDEO CARD: Single 1GB GDDR5 ATI Radeon™ HD 5870
MEMORY: 6GB Triple Channel 1333Mhz DDR3
HARD DRIVE: 640GB - SATA-II, 3Gb/s, 7,200RPM, 16MB Cache HDDedit
OPTICAL DRIVE: Single Drive: 24X CD/DVD burner (DVD+/-RW) w/double layer write capability


is this good enough to play crysis warhead with ultra high graphics without any lag, ?? and to play assasin creed, and call of duty? without lagg? and would it runs smoothly?

The 4870 x2 is by far the better card. 3200 streaming wooooooohoooooooooooo!

i understand that i would do alot better if i create my own computer, but you have to know that hardly know anything about computers, i dont know how the hard drive looks like, and didnt know what the power supply looked like, I basically hardly know anything thats inside of my computer.. i opened it and i couldnt even see where was the graphic card, i was have my uncle build it for me but he told me i better be off buying one becuas he lives in new york and i live in florida so if anything goes wrong, if any software become damaged, i wouldnt know how to open my computer and fix it, i decided to get this one

CHASSIS COLOR : Cosmic Black, Alienware Aurora Chassis
PROCESSOR : Overclocked Intel® Core™ i7 920 (3.2GHz, 8MB Cache)
OPERATING SYSTEM : Genuine Windows® 7 Home Premium, 64bit, English
VIDEO CARD : Dual 1GB GDDR5 ATI Radeon™ HD 5870 Crossfire™ Enabled
MEMORY : 6GB Triple Channel 1333Mhz DDR3
HARD DRIVE : 640GB - SATA-II, 3Gb/s, 7,200RPM, 16MB Cache HDD
OPTICAL DRIVE : Single Drive: 24X CD/DVD burner (DVD+/-RW) w/double layer write capability
MONITOR : Dell ST2410 Full High Definition Monitor

My uncle says its a reall good powerfull computer, i hope i can play any game that i desire with intense graphics without lagg. thanks for your help, its very much appreciated