How to do your housework with little ones in the house.  

For your one year old, you COULD try a playpen, but he/she might scream, or actually climb out. You could also try to get one of those huge makeshift playpens - the kind most people use outdoors - but again, they may scream, or escape.
I've been there, with a three year old and a one year old, and I don't remember how I managed - only that I didn't really get much done until my husband came home, because I was looking after them.
Some might nail me for this, but one thing you could try (it will take time) is to pick a network like Playhouse Disney or Nick Jr (whichever annoys you least), and watch it with them for several days. The one year old is probably still too young to really engage with any of the characters, but your three year old might become attached to a particular show or even several shows, and once he/she is engaged with a character or show, you should be able to get up and accomplish things.
Also, try talking to your three year old. Three year olds are usually eager to please, so if you designate your three year old as your "helper", you might also be able to get more done, and he/she may even be able to help you with the baby by keeping the baby occupied. For instance "Sweetie, mommy needs to wash the dishes, so do you think you could be a helper and play with your little brother/sister for a little while?" Set up something for them to play with in the room you need to work in, so they are still with you and you can keep an eye on them, but they may be able to keep themselves occupied for you to accomplish a few chores.
Good luck!