How can I buy a house with a 401(k) or a Roth IRA?

Please provide specifics regarding how much time the money has to be in the (Roth) account, tax consequences, age requirements, and any other relevant eligibility requirements. This is for my first home, not an investment property. Any website links with these details would be appreciated as well.

OK, let's narrow this a bit: if I take a 401(k) and roll it into a Roth, does the amount rolled count as "contributions"? I'm trying to figure out how I can access the money without being taxed. I'd like to use more than $10K to pay for a house.

You can use up to $10,000 of a Roth IRA without penality for a first home purchase, build. Using 401K results in an automatic 10% penality, then income taxes for your tax bracket.

any time but if you take your money out like 401 k you will pay a pennelty and tax on that money

Do you have any other savings to use as a downpayment? There are many first time homebuyer programs out there, some only requiring 3% down. Do not tap into an IRA unless absolutely necessary. I was able to show that money in my case , but I didn't have to cash it out. I showed the bank I had the money in the IRA and could access it in case of emergency and that was enough for me to qualify, I didn't have to convert the account to cash for my purchase. I had excellent credit and I had a downpayment...but no job at the time of my purchase. So, credit really factors in to your first house!