this combination is quite popular budget kit in European music shops. I think, for given money, it is really solid setup with nice warm tone, some guys prefer it to all hartke setup with HyDrives. Assumed, you've talk about MAG series of Ashdown cab, they have a eight ohm version 410T and four ohm version 414T Deep. I had heard eight ohm and precieved volume was fine for particular application. Using eight ohm version, you could possibly connect two boxes to LH500 as RickenBoogie mentioned, if you'll need more volume.
More expensive ABM series (blue speakers) give you better speakers and enclosure from birch ply, which leads to better clarity and punch at higher volumes, also have higher sensitivity (it will be slightly louder). But as i said, MAGs seems to me really fine for its price.
Just hint for comparisons, if you'd like to try it somewhere, Hartke LH series has volume pot with different characteristic than most bass heads. Intentionally, half of level isn't at middle of pot, it is progressive for having better control at lower volumes. So you'll have to turn volume more to achieve same loudness as on other heads.
Here is sample from German e-shop. http://www.youtube.com/watch?v=uD-umOMZDmc