System Restore will have perfectly eliminated any damage you did to the registry with CCleaner
But this is ASSUMING you restored to a point that preceded your cleaning of the registry.
System Restore also promises to restore all "System Files" which ought to include all drivers and your sound system,
unfortunately my experience with XP Home was that it never made good on its promises for all "System Files".
Please note that from what I remember of using XP two years ago
a Restore Point is NOT a single POINT but a "BLOB" which is compiled over a period of time.
It consists of a Registry Hives Snapshot that is taken at the instant the new Restore Point is created,
and then over a period of time it captures changes to so called "System Files".
Long story Short :-
If your system was damaged on Wednesday then perhaps you need to restore to Tuesday to repair the registry,
BUT that Restore Point will include "System File" changes that occurred between the start on Tuesday and whenever the Thursday Restore Point took over.
( I know that officially a new Restore Point is created at 1 day intervals but that was not my normal experience )
Just possibly you need to restore to the Restore Point that precedes the one preceding calamity.
System Restore was NEVER able to decide whether my Firefox Cache was a system file or a user document,
so when I did a System Restore it would leave in Firefox profile both a "cache" and a "cache(2)".
I love the absolute certainty that I have gained now that I use Image Backups,
which capture the precise state in one instant of time of all registry hives and system files and all my Applications and User Documents.