I discovered recently in XP if I held down shift on a Word Document or Excel file that there is an additional menu open that reads:
"Open as Read Only"
Upon selecting it Word Launched with my docuement it it. Much to my surprise, however... is that Word wasn't in read only mode!
However, after a bit of Google-ing for a solution I finally came across this discussion in 2006 on this very problem... with the fix from a Microsoft MVP:
"open as read-only" office applications - microsoft.public.office.misc Google Groups
I don't know if this is a "fix" that MS has ever pushed out (and perhaps my company never distributed internally...) or if this is something that has remained broken. I'm also really curious what Office 2007 will do on my Vista Ultimate laptop at home.
Anyway... I've always wanted to be able to do this and I thought it was impossible and useful enough that other should know about it.