I played Atreides first, then Harkonnen and finally Ordos. Missions are quite easy in the first four, and hard in the last three. Perticularly, Atreides Mission 8, Harkonnen 7 and Ordos 8 are----well, I replayed them several times to get through. In any of these missions the core objective at the start is defense. If you can stand up to the early assults, victory is coming close as the opponents never protect their harvesters well(of course attacking them will trigger AI attacks). I use rocket turrets as the core for defense. I build wind trap-refinery-barracks-outpost(and sell immediately)-rocket turrets-second refinery(and then sell in order to get an additional harvester)-more rocket turrets until you nearly cover your opening(I did that in Harkonnen 7 and ordos 8). In mission 8s against Ordos, put infantrys behind entrances and there will be no problem. Usually I don't build light factory because these vehicles are too light-armored. Combat and Siege tanks are enough for defense. When I have enough units for counter attacks. I order 5-6 quads from starport and search for enemy harvesters. They detroy harvesters very quickly. When enemy comes out, my quads have already left! When your harvesters are under attack and it's too late to save them, order more harvesters. In Atredies mission 9 I found out I had over 20 of them in the end of game! In all, Dune 2000 missions are harder than Red Alert. In Red Alert 1, the opponent rarely attacks, allowing me to build numerous tanks and crushing them. :)