If I were you I'd do it in one fell swoop and get it over with. The water pump (if it's the original), the lower and upper intake gaskets, coolant elbows (I've had great luck with the aluminum ones) and maybe even valve cover gaskets if they're also original.
Look at where the heads meet the lower intake. If you see a black/plastic gasket, you'll definitely have to replace it soon. If it's a silver/aluminum gasket (the newer style) then you can afford to wait a bit, but really the sooner the better. You never know when it might get worse and cause you to ruin something on the bottom end.
