How much ram should I get?

[og5]

Just got an awesome deal on a Emachine D3024 ($236 w/o monitor at office depot right now) The specs are ok for everything except the ram, only 256 mb. I want to be able to 4 table while datamining another 3 skins (16 tables) do you guys think another 512 mb would be sufficient for this or am I going to need more?

Thanks