I am in the same situation and just this morning I was asking myself in the shower "how am I going to do all this?" now that I have a 2nd baby on the way. My children will only be 20 months apart and although I'm thrilled I also wonder "what were we thinking!!!" Here are some tips for you. I've put some of them into play and others we plan to do in the future.
Cleaning lady - Excellent idea! If you can afford her, by all means let her clean! I also like the idea that a few other ladies had to hire a college student to run errands, do laundry, etc.
Commute - I drive 2 hours a day, roundtrip. This is my quiet time. I sometimes catch up on phone calls I don't have time to make at home, blast the radio, liten to nothing (my favorite) and I love books on CD. It lets my brain drift off into thought and I don't have time to read anymore so it's nice to do it somehow. Your library has them if you don't want to buy them.
Errands - As another mother suggested, run them on your lunch break at work. I have a tendancy to work through lunch so this gives me a mental break from work and I get something accomplished for home.
Food - Have groceries delivered or have prepared meals delivered. I honestly can't wait until our finances allow for this! I've tried the crock pot but get burned out making the same 4 things. Also, I'm no good at lasagna and haven't found a lot that I can make in big bathches that we will actually WANT to eat for several days. If you're any good at those things, go for it. Otherwise budget for delivery.
Schedule - Keep a family calendar in the kitchen or place where everyone can see it. That way everyone knows who's working when, who's taking who where, etc. Also, get your kids involved in play groups, after school programs, sports, crafts, boy/girlscouts, etc. You don't want them in something everyday but keep them busy so they're not thinking about you not being home yet by 6:30. Make sure they have their own life and schedule. Just make sure their activities are on days someone's home to take them and arrange with other mothers for picking up and dropping off so you don't have to do it all.
Personal time - What's this? I really don't have much of this anymore. My child is very young still so I'm not happy being away from him too much. Work takes me away enough let alone leaving him to go out with friends or something. I have maybe 1 day a month to do something for myself but that's because I choose for it to be that way. Like I said, my time is my commute time. Not that I really enjoy it but at least I can be alone, quiet time.
Date night - Very important! Set aside time weekly, or bi weekly, for the 2 of you to get out and do something. We go after our son's in bed so we're not taking time away from him and go to a movie, for a walk or just to sit and talk.
Be realistic - You're not going to get it all done! This is something that's taken a while for me to get. I like an immaculate home but I've had to give up making everything perfect and realize the mail will sit on the counter, I will not always be able to see my reflection in the kitchen floor, there may be dishes left in the sink, etc. Oh well. As long as we're fed, dressed in clean clothes and happy then I have to not care so much about how the house looks.
Laundry - Do 1 load everyday. This will help keep it in check and not pile up.
Childcare - Find a sitter or center that you LOVE. If you don't LOVE it then you're going to feel more guilty. Or consider on Au Pair if you can afford it. So that way your children are in the home being cared for.
Employer - They're going to have to understand that you're going to need time for your children (sick days, doctor visits) and if they don't, then talk to them about your rights under FMLA. Also, if you have a really good relationship with them, ask if you can work from home at all. If that won't work, then maybe you can take a different positon in the company that will allow it. Or just keep your position and make the best out of it.
Vent - Make sure you vent a little. If you go to the gym, go for a run, scream into a pillow or just need to cry, then do it. Let out some steam that helps you cope with it all. However that may be.
Well best wishes to you. Running a home, having children and being successful at work is VERY hard. Just take it one day at a time and don't overwhelm yourself. *hugs*