SP2 may contain "generic" MS driver updates and things like DirectX 9.0c but not specific videocard/soundcard type drivers. So it is highly unlikely you will have to reapply specific gfx/snd/mobo drivers you already have. In any event, if SP2 finds later versions already installed, I would expect it to ask before overwriting a newer version - MS have certainly done this in the past.

Like you though, I see no reason to apply SP2 as yet and I will backup my whole system before I do!

Tomcat