I have just rebuilt my hard drive after a Windows Vista crash but have been using Office 2003 for years and I have never seen the following annoying behaviour before.
When I open Word2003, a blank document opens and the various menus and toolbars are displayed. As soon as Word finishes opening, I am presented with the "Save As" window. It suggests a document name of "Doc.doc". When I choose "Cancel" the window goes away, but then immediately reappears. When I click "Cancel" again, the blank document is available for me to begin work.
Also, in Word previously, if I opened a new Word session and opened a document from the Recent Documents list immediately, the first blank Word document disappeared—something that I found very convenient.
Word is SP3 and Vista Business is fully up to date with SP2.