Thoughts on the Roth 401K and AMT

Recently my company announced that they would be offering the Roth 401K to all employees. I was very excited about this since I had contacted HR asking if they could make this offering available. At first I thought that there was no question that I should contribute and contribute the max to the Roth 401K. Now here are some things I'm considering. I don't have any of the right answers, so if anyone out there has experience or more information on this topic, I would appreciate it.

1. Contributing to a Roth 401K vs. a regular 401K would reduce my take home pay since the regular 401K is a pre-tax deduction while the Roth 401K is an after tax deduction. I should calculate how much this will reduce my take home pay since C and I are aggressively saving to buy a home.

2. Since a regular 401K is an pre-tax deduction, this reduces our overall AGI (Adjusted Gross Income). Does this have implications on whether or not we will have to pay the AMT (Alternative Minimum Tax)? The AGI is your adjusted gross income which is what your federal taxe are based on. The AMT is a tax that was originally supposed to be levied only on the wealthy, but the salary guidelines were not inflation adjusted, hence it's starting to affect more and more middle class taxpayers (I consider my husband and I upper middle class). Some good links to the AMT are here and here.

I don't know what to do and I have no idea how to figure out if the AMT will affect us in 2008. I guess if we have to pay AMT in 2007, that would be a sign that we may need to pay it in 2008, although I expect our income in 2008 to be $30K-$44K higher (I received several pay raises in 2007, but my overall pay in 2007 was probably $10K-$15K less than my ending annual salary plus I should get another pay raise for my overall 2007 performance and C received a higher than expected salary increase). I don't think we will have to pay AMT this year since we don't have a lot of deductions (I think we donated less to charity than the standard deduction), so I'm hoping we'll be safe!