This is a situation where paying the extra few $$ for TurboTax Premiere really pays off. I sold some raw land in 2005 on a 10 year RE contract. I opted to spread the reporting of the capital gains over the long run since my marginal tax rate is due to drop dramatically when I retire next year, making me eligible for the 5% cap. gains rate.
I just plugged all the relevant numbers into TurboTax and it did the calculations and spit out the appropriate forms.