Vista Upgrade problem

my PC is able to run the Windows Vista Home Prem dvd i bought

at the moment im running Windows XP Media Centre Edition with all the
updates installed

when i enter the Windows Vista upgrade disk all i get is

a readme file which says

"This disc contains a "UDF" file system and requires an operating system
that supports the ISO-13346 "UDF" file system specification."


Anyway, i tried it on my other PC running Windows XP Home Edition and the
disk loaded fine (i didnt install)

i then updated my DVD ROM's firmware and still nuffing

so why doesnt WinXP MCE support the above and Home does