many thanks for the detail answer
--- one last Q --
how about , clustering and (or network load balancing in the windows 2003 server itself)
and
adding one more server computer, and using Master/ Target features of SQL server 2005
for the above methods
will there be any thread in SQLserverCentral.com that would tell us- about the precaution (or procedures) during such upgrade
=== for the CRASH that I mentioned earlier, is it the mistake that I try to upgrade with the same instance name -- during new installation===
thanks for all your guidance