rough rule of thumb for system one uses to work (as in work with audio) if it aint broke don't fix it
if you are relatively secure via isolation then upgrading purely for the sake of upgrading (as long as system is stable and performs like you want) makes little sense. MS never explains, to consumer, things that are altered in patches and upgrades and all sorts of things can have unintended consequences
in the move from XP to XP sp2 the way firewire was handled changed in a way that adversely effected a number of audio interfaces, for example.
If things remain consistent with past if & when a Win7 sp2 arrives it will contain all relevant intermediates, and typically MS has supplied a free disc to registered owners.
a patch necessary in improve performance is a different matter and then if you wish to remain un internetted slipstreaming (down load on one system install on another) is your option . . . but you'd want to go to MS web site for that info in any case