Wait, so you can buy Dawn Of War: Gold Edition and Dawn Of War: Dark Crusade seperately for £3.39, or together for £3.39?
That's... odd.
Also, how are they?
Dawn of War Gold just includes the Original + Winter Assault. Dark Crusade is a standalone game that's done in a more RISK / conquer the map style presentation than the level 1, 2, 3, etc style campaigns in the first two titles. The original campaign is really well done and worth the package price alone if you enjoy single player RTS campaigns, one of the better single-player RTS campaigns I've played. I didn't enjoy Winter Assault as much myself, but it was still fun for the first time. I've replayed the original game a few times.
As for DoW 2, I haven't played much Retribution yet, but Chaos Rising >> the original game. The missions are more varied and story is more enjoyable. It plays off the story from the original DoW 2 though, so it's still worth trying if you can tolerate it (skipping the extra missions helps speed it along).