No, thats not right because 4x1gig would give you twice the RAM.
But 2x512 = 1gig
1x1gg = 1gig
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the 512 sticks are better
Don't get 4 512 sticks unless you're sure your motherboard can do the 400mhz on each stick with every DIMM filled, many can't.
Right now you don't need 2 gigs. Anyone who has 'thought' they needed it or something because of BF2 and asked me about there has always been stuff on the comp taking resources.
BF2 runs PERFECT on a gig of ram, there is no need for more.