Well if you don't mind me using an AMD CPU here we Go...
AMD PhenomIIX4 955 Black (Quad core, 3.2GHz unlocked multiplier so it's easy as piss to overclock) You could get the six core version, but that's moar money. This is around $140 That's around $200. alternatively you could get a cheap CPU and overclock it a bit like a Phenom X4 820 which is about $100. Lastly, an Athlon II X3 440 (triple core 3GHz) is around $80 and MAY have a locked fourth core which BOTH of the motherboards could unlock. Unfortunately my fourth core was slightly unstable and occasionally things crash. I also had a locked L3 cache so it became a Phenom II rather than an Athlon II
Now, I have two motherboards to recommend, Both have DDR3.
1. Gigabyte GA-890GPA-UD3H (890GX Board, therefore more versatile expansion possibilities) $140
2. Gigabyte GA-890FXA-UD5 (890FX Board, therefore more specialised expansion for graphics) $180
The 890FX board has two LAN ports, and setting up Crossfire/SLI requires a moment. PCI-eX16 ports 1 and 3 share bandwidth 2 and 4 do as well. if you're only setting up two cards do it in ports 1 and 2, if you're crossfiring 3, but the best one in slot 2 and put the other two in 1 and 3 to get the most out of the cards
Hard drive. Nice and simple here Samsung Spinpoint F3 HD103SJ I have one, It rapes... You can get more if 1TB isn't enough but one is about $60... If you have a fuckton of budget, you may want Solid State Drives. They're supposed to be fast as fuck and last longer than "Conventional" hard drives... but you're just pulling your old ones out right?
RAM. this could easily be anything you want, but it's important to get this right. My budget was short so I got some shitty unbranded RAM. Corsair do a good deal, two 2GB sticks, 1600Mhz with pretty tight timings. For $70 maybe less, these things are quite good. the tight timings and hight clockspeed mean it's quite fast for DDR3 RAM, I can't remember the model though
Should be killer for gaming though... again, you're jut pulling your old RAM out.
That's all the basic shit out of the way, next you need POWER! You have a few choices for a PSU. Anything would do, maybe some Eco-friendly PSU if you're so inclined? Just get something with AT LEAST 550W! That's a bare minimum, around 650W would be lovely more than 800W is sheer overkill. Anyway a nice, quiet 600W PSU is around $90
Here's the important bit... Graphics Card. Get something awesome. I've been out of touch regarding the graphics card war between ATI and NVidia. Someone else could help you out more here, but a ATI HD5850 is a pretty powerful card with DX11. $200 is a lot, but this is where you make or break your machine with regards to Crysis 2. Heck, it's probably not enough muscle anyway.
You could multi GPU, both motherboards will dual crossfire/SLI but only the 890FX boards will tri or quad GPU
Could someone recommend a Nvidia card to compare with this?
Ok so say you went with the 890GX board, Phenom X4 955, got one hard drive and decided to crossfire. This is around $650 now, so we're running out of money... but you still need a case!
This is personal taste, but a decent case is about $100. Then all you need is a keyboard, mouse and monitor! You may be able to save a ton on the Graphics card if my info is outdated. Also, if you want a blu-ray drive add like $80 on to that
