Look at hardware and what your going to use your computer for ( software application, games,we browsing, whatever). Look at what you want to spend. Do your research and make a decision.
Get the correct motherboard for your CPU. Get the correct RAM. Get a good Power Supply.
The fx amd cpu would be good if all the game and your usage is multi threaded, single thread app the fx is not as good. I have looked at benchmarks and the fx does well with crysis or whatever it is called. That game is multi threaded.
If I were to rebuild right now and spend a 1000, I would go Intel Sandy Bridge.
Now if I were to go 600 700, I would look more towards AMD phenom.
This is just me. I would not go with fx because I don't think it would serve my purpose for the use of my computer.
Just my opinion.
from a different perspective, I have built and also use both an Intel i7-2600k 3.4 GHz Quad-core PC and an AMD Phenom II X4 Q975 Black Edition Deneb 3.6GHz Socket AM3 125W Quad-Core PC
and playing Aces high, the AMD cpu using just ONE core runs Aces high maxxed out with all settings maxed except shadow textures is set at 4096 instead of 8192, AA at login video settings screen is on notch 3 screen res is 1920 X 1200 steady at 60 FPS
my Intel i7-2600K runs the game using TWO cores the exact same performance , it is still maxed out at 1920 x 1200 ( and or 1920 x 1080 )....... only difference between the 2 computers is that the intel has an XFX HD6950 2 GIG VC and the AMD has an XFX HD6870 1 GIG VC ( well their are a few minor other things like different type of Sound Card and the i7 is running a RAID 0 setup using (2) 128GB sata III SSD's while the AMD is using just 1 128 GB sata III SSD )
I currently have 3 computers running with AMD phenom II cpus ( 2 quadcores and 1 dual core ), and I hopfully will be updating all of them to the AMD FX AM3+ series, if I have enough money left over after my oldest Daughter's wedding at end of Dec. ...... I will be looking for the Rev B version of the FX4100 cpu, though ....... these new FX AM3+ cpu's run cooler, they are on newer technology and they are les power hungry.......
The only thing that my i7 cpu does better than my AMD Phenom II 975 cpu is Video editing/ripping/coding/burning etc........ my AMD cpu blows my Intel away when I am working with my AutoCad and for gaming it is a wash between the 2 different makes......
now you said you are wanting to build a new Computer and you are going to be playing 3 certian Named mmo games: Crysis, Metro2033 and BF3 ....... 2 of these 3 games as I posted earlier are of the most extreme demanding pc games for cpu's / gpu's / systm ram....... if you are building your New PC to play those games and you want better than mid level / middle of the road playability, then you will certianly need to step up all components of your PC meaning PSU, CPU, GPU, HD, Case & Case Cooling, CPU & GPU cooling
if you are only going to be playing Aces High, then as Drano posted.... the i7-2600K & 6950 2 GIG VC is overkill .........
I recently throwed a system together for a friend...... it was an old Athlon II 6400 dualcore 3.2GHz AM2 cpu, ATI HD3870 512 MB GDDR4 VideoCard, 4 gigs of PC6400 DDR2 800 MHZ Ram, 750 watt PC P&C PSU and a 320 GB sata II HD with win7 SP 1 64 bit as the OS......
it ran Aces High with most settings maxxed except shadows turned down to 1024 and AA set at x4 with 512 textures and held a steady 59/60 fps using 1920x1080 screenres....... turning the hi res skins textures on and it still ran a modest 48 to 52 FPS and never below 42 FPS in some of the thickest furballing / smoke / fire etc....
so as mentioned above do your research, and then research some more......... you said you will be doing this in a month or 2, so you have plenty of time to do some solid reviewing and comparing....
as for staying with the same brand or staying with AMD cpu / AMD-ATI GPU vs intel / nvidia matchup........ most of the Motherboards today will accept both types of Video Cards the intel/nvidia AMD/ATI myth is almost completely removed from the equation these days with only a very small few exceptions to where you might run into a problem...... meaning you can use ATI or nividia on both Intel & AMD MB's and not have a problem...
and remember, each of us posting here are posting a personal opinions.......... although some of the recommendations posted are coming from current or previous experience.....
whether you decide Intel or AMD for your cpu or decide Nvidia or AMD/ATI for your gpu .......... is all up to what you desire ........ you can make any combination work
as for Intel being easier and less problematic to build ......... they both are just 1 part of the whole PC..... as posted it is as easy as Lego's to build a PC....... the hardest part is researching and deciding on a good matched set of components then loading / installing the OS and setting the BIOS settings ........
Do not Be Affraid to post and Ask questions
Good Luck on your New PC build adventure
edit: I don't pay much attention to most of those benchmarking results articles/reviews ...... I find that I get more from "Real Life / Real World User results/ experience" than I can get from some lab telling me something is a leser product when my own personal experience using the compnents they are benchmarking is giving me arguably different results than what they claim........ but as always the case YMMV
TC