I asked a question in the microsoft.public.windows.64bit.general newsgroup about installing Win7 in a dual- or multi-boot configuration. A part of the answer I received said to boot into XP and run the Win7 32- or 64-bit setup from there. Doing it this way would preserve the users existing drive letters and names and would also add a boot option for Win7. (The question is: "Win7 multi-boot" dated 07 May 09 - if anyone would like to read the question and the answer and to make their own comments - good or bad - or why this method is better or not.)
I have not tried this method or to boot from the DVD yet. Still gathering information, both pro and con, as to what others have, so far, experienced.