One question I get all the time is how long should I keep my tax records? Well for individuals the minimum you should keep is four years from when the return was filed, so in January 2011 you should keep at least 2006 records on. As far as records of stocks and real estate purchases, you should keep them until you sell them, then for 4 years after that. This is the minimum. If you have questionable tax items on your return you might want to keep them a little longer as the IRS can go back an unlimited number of years if it can prove fraud – and with the IRS fraud can be a nebulous thing.
For businesses it is a good idea to keep 10 years of records just for comparison purposes and other reasons even though the statute of limitations is the same.