Athlon 2400+ with 120Gig HD (8Mb buffer), 512Mb memory running XP Home, set up with 4 users, all unlimited use. Using Word 2000 to open existing documents.
In one user it is virtually instant, in another it takes about 30 seconds. It is not related to document size and even with both users 'current' one is till fast and the other very slow. It also does not matter whether the document is on the desktop, in My Documents or even on a USB2 external hard drive the huge speed difference remains.