Solved: Windows File Protection

I have WinXP Home with SP2. While investigating a Blue Screen i ran sfc /scannow. I rec,d the message "Files that are required for Windows to run properly must be copied to the DLL Cache. Insert your Windows XP Home Edition Service Pack 2 CD now". I have the required CD and installed SP 2 right after it came out. My question is: "When it asks me to 'install now' dosen,t that mean to install all of SP2 ? or will i be able to find on the cd just the files that re required to be copied to the DLL cache? or is it safe to uninstall SP2 and reinstall it from the cd? or will i last till Feb. when i plan to upgrade to Vista? Any thoughts please.