Actually the difference is how and what it installs.. for everyone I recommend the network install and not Windows Update..
the reason for this is because the Network install will replace all windows files to the latest version available and effectively turn all system into XP Pro, reguardless if you hav eHome editon or not.. everyone will be on the same lever and support for their system will be that much easier and system tweaks and settings will become unified instead of having a set for Home and a set for Pro.. the Windows Update version will only update components specific to your version of windows and leave out all the other stuff.. sudch as home edition will still be Home edition without the Pro enhancements and services and capabilities.. the Home upgrade is 80 MB, the pro update is 100 MB, the network install is 266 MB and completely reinstalls windows, but will not change your current settings.. however it will add any windows XP components that may have been left out in any version of XP...
that is the major difference...
you can either have a partial update, or a full update.. your choice..
Also, Windows media player is about to release v10 .. as such media Player v10 Beta has been our for 3 months now and works fantastic....