Really, it depends, if its a casual fun game, maybe 10 seconds, if its an intense cool FPS, more than 1 minute would be fine (kinda cool side scroller, some where inbetween). I prefer 1 big load, then at most a 5-10 second load between maps. Yeah 1 gig of ram seems to be common, most new basic computers have 3 or 4 now.