Sorry but you and your husband are at blame here, regardless of how many diplomas the tax preparer had in display. It is your obligation to review your return and ask questions. A tax preparer files taxes with the information you provide, so how is he at fault. Have you contacted him? What did he say? Is he willing to review your return, and verify that the letter is correct?
After you talk to the preparer and find out you do owe all you have to do is reply to IRS, follow instruction on the letter on how to reply or correct your return, After that if you still owe then either contact IRS by phone at 1-800-829-09922, or write IRS or download Form 9465 Installment Agreement Request from the IRS website www.irs.gov. The minimum payment IRS will accept is $40 per month (IRS grants 60 month installment agreement) interest and penalties continue to accrue until you full pay the amount owed. If you can't pay, since both are unemployed then contact IRS explain your situation and they can label your account "currently not collectible". but you must contact IRS and explain why you can't pay, don't ignore the IRS or any bill collector, No one knows your situation, and without an explanation from you, they will think you are just refusing to pay.
Good luck; when you file your 2009 tax return IRS will offset your refund to the debt if your account has been assessed. If you just got the letter that you owe for 2008 and you have 30 days to respond, then your account doesn't show you owe yet, so file now so you can get your refund.