my computer only has 812 gigs of ram and i do fine but i cant play with a lot of detalil though..
but performance over quality 
i also had my video card set on low too.. but is it just 2142 being laggy or is your whole computer being sluggush? but what ty said may be a solution to your problem
but yeah, vista eats up quite a bit of ram so i do suggest getting xp but it really is your choice whether you do it or not, its all up to you 
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