how much RAM would i need for the Giant Earth Map?

I have just ordered another 1gb of ram for a total of 2gb.i am using windows xp.would this mod run ok on my computer?

I have 2 gb and it lags. Try 4 gb - or just buy a new comp.

4 gb.

It depends on how you define 'ok'. I have only 2gb of ram and I designed, developed, tested and played GEM with it since day one. I am satisfied with the 30s ~ 1min wait between turns. Obviously 4gb would be better, but don't be scared out if you don't have that.