Nice query, neatly formulated, thoughtfully articulated. Where'dja grow
up, kid?
The "express inatall" is a long online session during which the MS site
downloads and updates your system with the necessary update files. There
is no residual file that can be used to repeat the service pack install.
Need to reinstall the SP? Go online again, endure the pain.
The "network install" is a long download session which places the entire
svc pack file on your hard drive as a self-exploding install file. It
can be used over and over, on any syatem including the one you're
interested in right now. It's a pretty good choice. It's also available
on CD for a nominal shipping fee from MS.
Nobody but MS can tell you why the nomenclature. It's gotta be another
marketeering mystery. Why let language get in the way?
