All right, I've read through the last 50 pages of this thread.
From what I've gathered, I'd be able to run ArmA 2 at high/very high settings and get pretty good FPS with a i7 CPU and Radeon 4890 GPU.
I'm looking to build a whole new computer, so far I've picked out:
ASUS P6T SE LGA 1366 Intel X58 ATX Intel Motherboard
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131386
Intel Core i7 920 Nehalem 2.66GHz 4 x 256KB L2 Cache 8MB L3 Cache LGA 1366 130W Quad-Core Processor
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115202
ASUS EAH4890/HTDI/1GD5 Radeon HD 4890 1GB 256-bit GDDR5 PCI Express 2.0 x16
http://www.newegg.com/Product/Product.aspx?Item=N82E16814121308
OCZ Reaper HPC 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1866 (PC3 15000) Triple Channel Kit
http://www.newegg.com/Product/Product.aspx?Item=N82E16820227379
If someone could recommend to me a good case + PSU, I think I'd be all set. I used Antec on my last build, and I like their cases, I was looking at this one:
http://www.newegg.com/Product/Product.aspx?Item=N82E16811129037
EDIT:
I wound up getting an Antec 650W power supply and the Antec nine hundred case. Got a Sony DVD/CD ROM reader and Samsung SATA HDD. I can't wait, should all be here in the next few days.