In case if anyone else has this problem...
I had trouble printing envelopes with Word 2000 on on my hp LaserJet 1200 printer. (cxoffice 4.1, Fedora Core 3) The envelopes would always print on the top, even if it was set to print in the center (or anywhere else.)
I found a solution by changing the printer driver from 'pxlmono' to 'hpijs'.
This seems to be a rare bug. I noticed that it was reported in Ticket 36766, where the customer was also using a HP printer and a Red Hat distro. So, it might be a combination of the three.
MWM