can I file a 1040-x I received my 1099-misc form after I filed my taxes in 2005

If you discover that you owe tax - yes. You should file a 1040-X and include the income from the 1099. Assuming you owe additional taxes, be aware that you will also have to pay interest for the late payment. But if you are looking for a refund because you now realize that you overpaid 2005 taxes - then no. To claim a refund with 1040X, you have 3 years from the time you file your taxes, or 2 years from when you paid your taxes, whichever is later, So if you filed your taxes for 2005 in April 2006, you had until April 2009 to file an amended return looking for a refund.

You can find 1040-X for tax-year 2005 on the IRS web site - see:
http://www.google.com/url?sa=t&source=web&cd=1&ved=0CBcQFjAA&url=http%3A%2F%2Fwww.unclefed.com%2FIRS-Forms%2F2005%2Ff1040x.pdf&ei=mU5fTIXaC8GblgfsusyXCQ&usg=AFQjCNGL_O025baT0Mp4VxeY9NvqpD7DEA&sig2=8fR_TsLltor4u2Nl3-kNMw