As a general answer to the people asking whether their rig will run the game:
About CPUs: Generally the faster the better. A 2.0GHz quad or a 2.2GHz dual core is definitely enough, but if you want to raise settings like object detail to normal you'll need at least 3.0GHz.
About GFX cards: As a general rule, fast single GPU cards are the safest bet for Arma2. Some people have allegedly been able to get dual-GPU cards and SLi/Crossfire setups to work properly, but it seems to be very difficult. The 8800/9800 GT cards seem to be the threshold for medium-high settings. The GTX variants are better though, obviously. 8600/9600 GT/GS cards are enough for low settings (maybe some settings on medium with the GTs) - but don't worry, the game still looks great on low. If you want to play on high-very high settings, a GTX285 or HD4890 along with a fast CPU are definitely a must.
About RAM: I'd say 2GB DDR2 is minimum, 4GB is optimal. Again, the faster the better, but you probably won't notice any slowdowns with 667Mhz.