If you want to make it acceptable for arma 2 then upgrading your video will pretty much be enough I guess. Half a year back when I had quite a shitty PC with 2gb ram, intel pentium 4, and HD4850 (I know the CPU made a really small bottleneck ;) then I was able to play it with about 10 fps. Considering your ram and cpu to be better, then video is most probably the one holding the game down. If you want to upgrade the PC to a level that upcoming games will run smoothly then you need to upgrade all 3 parts (not sure how much power you will need). If you are running win 7 then this will always occupy a bit more than 1GB of ram, so you have 2BG left for games, which is not enough. "My friend said you need to have the same RAM cards." He is right, RAM of the same type cooperate better with each other (same brand and size). Radeon HD 6850 is very good for its price, GeForce GTX 460 is also good. Not sure which you prefer more: radeon or geforse, although the price is basically the same, 6850 is a bit better. Both of these are better than the suggested GTX 550 and the cost is same for all three. I just recently (in winter) upgraded my PC to: i5 2500k, 8GB RAM and kept the hd4850 as it still holds on quite well and I can play pretty much any game with max graphics settings (1600x1200 screen). But I'd recommend upgrading RAM also. How many RAM sockets do you have? If you have 2 then 2x3 or 2x4 will keep you going for many many years. (2x4GB are more common I think) If you have any questions or suggestions, then I'd be more than happy to reply. Andres