I personally think that anyone with kids under the age of about three or four should have a part-time maid, just to help try to keep the house halfway decent looking. And I think the maid should be mandatory and paid for by the government. Europe gives their parents a stipend for every child they have, to help defray the costs of raising children. We get no such help. If I had to chose between money or a maid--I'd take the maid, hands down!
I only have one child and I was completely and totally overwhelmed (she's also special needs, so enough said). Having two children under the age of three--honey, with a newborn, you're lucky if you can pull yourself out of bed every day. Getting meals on the table is a tremendous accomplishment in and of itself. The worse thing you want to do is make yourself into SuperMom and then have to worry about adrenal fatigue (which I have and is no fun--going on two years of making myself healthy. Any time I stay up a little bit late or have a very intense and busy day--I'm shot for the next day or two).
I don't think guys/husbands totally understand just what moms all do and how hard being a mom is. Putting aside the sheer aspect of giving birth and putting our bodies literally through the ringer (he'd be dead and tired and sore for days too if he had to push a little one out into the world), bringing a newborn home to a household that already has a toddler--well, let's just say if you get any sleep time, you're doing wonderfully great!
What I'm trying to say is, as long as the house isn't certified a fire hazard and the county dept isn't going to come in and condemn it, it can be less than spic 'n span. Once your children are no longer wee ones you can get back to having a wonderfully clean and spotless house. You're not going to have that when the kids are little anyway.
If you want to try to stay on top of the mess--so it doesn't get huge--see if you can budget in a weekly or a bi-monthly maid service that can come in and give your household a fairly good cleaning. If you can afford it, that might help give you some peace of mind.
When you're a mom, the most precious things you should be concerned and worried about, in my opinion, are raising the children. The house is important (esp. keeping up the outside of the house and the grounds), but the inside isn't such a big deal. You and your family are the ones who will be living there and will see the house daily. The level of unruliness depends on how much/what you can take. Can you live with a little clutter and a little dirt? If so, I really wouldn't let it bother me. I know others who are neat freaks will probably freak out at what I've typed, but really, I'd rather spend my time with my child than cleaning my house all day. If that's all I'm interested in doing, then I should have gone into housekeeping and not into motherhood.