|I would'nt monkey around with them either, Windows WILL go bananas !|
I couldn't resist.
However you can delete the entire contents [almost] of the \System32\dllcache folder to free up lots of space after you have backed it up first to a DVD-+RW or whatever, this I've done safely and to hell with SFC. Both folders get added to occassionly. "Drivers" is definately needed and all aboard it but 'dllcache' is a back up of system and other files in case something goes wrong, I never liked it which is why I nuked it and never suffered for it.
Maybe best to leave well enough alone on both counts.