Do I have a bonafide contract?

Being familiar with the lengthy real estate property contracts in the state of California, I have an unusual situation where the following applies:
1. Seller is a private party that made me aware his home was for sale and he needs to get out from under tax liens and such on the property.
2. Until he had all the facts on the $ amount he owed he was hesitant to write any contract with contingencies or otherwise.
3. In an effort to have him show us good faith once we put our home on the market (curr res equity=downpayment on her home) we asked for something on his part to show we would have a set sales price and not be hung out to dry once we showed our good faith of putting our home on the market and obtaining formal loan approval for the purchase. (All of which we did.)
4. He responded with a 2 paragraph "purchase agreement" that in his mind would solidify the price....I on the other hand was much more encouraged with the verbage HE chose and put before us, as I believe it constitutes a bonafide contract and does not pin us down with the contingency of selling our home or to close by a specific date.
5. "Agreement Verbage":
Agreement To Sell Real Property Located at 1234 Main St, USA
This agreement is made between the Seller, Mr. Smith, owner
of property located at 1234 Main St., USA and the Buyers, M/M Jones, husband & wife.

Mr. Smith, Seller, agrees to sell his property located at
1234 Main St, USA to M/M Jones, Buyers, for the amount of $123,456.
This is the last and final offer for said property.

Signed and dated on xx/xx/2005
(Signed by Mr Smith & M/M Jones)
6. Our home has not yet sold and the Seller in a rather backhanded way has procurred a non-contingent "back-up" offer thus jeopardizing our ability to purchase the property according to the Seller....Is he right or do I have enough to hold him to sell us the property only...especially given the last line of the "agreement"?
7. We're in a crunch now as he supposedly has received a letter from the IRS with a looming date to have all the IRS liens on the property settled. SOS

You really need an attorney to look at the contract and discuss your options. Alot of factors go into the formation of a contract besides the written word. If the attorney feels you have a valid contract that does not rest on the fact that you must sell your house first then the attorney can write a demand letter to this individual explaining his options.