When your Mail Format is set to HTML, you can have a selection for Stationery (the background). Just set the Stationery to "None"
(See Tools>Options, Mail Format tab)
I have Vista,AVG 7.5,Spybot S&D, ADAWARE SE Personal, Spyware Doctor, Windows Defender.
I have Office Outlook 2007. When I create a new email, the background of the new blank email has what appear to be a pattern of rows and columns of a flower, probably a rose. I did not set the background to do this and do not see where to remove this. Could it be a virus? Nothing is detected.