Basically, your basis (cost) in the land is what your parents paid for the 10 acres in 1965. You received the land as a gift, the basis in the gift is the donor's basis (parents) plus what ever gift taxes (if any) were paid.
When you sold the land, you have the selling price, less the basis (cost; 1965 prices) = long term capital gain.
The gain will be added to to your gross income/taxable income. Since it is undeveloped land, and you basically held it for investment, it should be taxed as long-term capital gain.
What you need to figure out (if it hasn't all ready been done) is what your parent's paid for the land in 1965. That is your basis...not when you received the land in 2007.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
**Disclaimer: Effort has been made to offer correct information; but due to the discussion forum limitations, the poster disclaims any legal responsibility for the accuracy of the poster's response**