401k Withdrawal for a house?

I know it isn't the greatest thing to do but who has done it and do you regret it now?

We are looking at houses and are trying to come up with the down payment asap and were wondering if anyone has done it for a down payment on a house and if it was worth it in the long run? I am 30 and have about 12k in mine right now. If I pull it then as soon as it lets me start dumping money back into it do you think it will be ok?
We need about $8400 for the DP and after taxes and the 10% ding for early withdrawal it should be enough and unless someone buys my truck pretty soon this is the next best (and fastest) way I can think of other than dealing meth and blow or selling my fine behind on the streets.

Isn't there a $8,000.00 Tax credit right now for home purchase before the end of the year? That would pay you back you're DP right?
My $.02, but check into first ask you're tax guru.
Good Luck!8)