>- by avoiding an upgrade, you won't run into weird incompatibilities with device drivers, antivirus etc.
incompatible driver was the snag I ran into when I upgraded from Windows 3.0 to Windows 3.1 -- Windows would crash toward the end. Luckily I'd backed up everything prior to installing the upgrade. Entire process took 15 minutes and 3 hours -- 15 minutes to complete once I'd figured out what was causing the crash. It took about 3 hours of repeating cycle of install -> crash -> restore system -> reconfigure -> repeat.