Scannow, looks for XP CD; won't accept.

Ran sfc /scannow (under XP PRO SP2), and it asked for the CD and I fed it the to E: drive and ran into a "feature" that "MS is aware of" and describes on their site in several pages about scannow, with varied attempted workarounds, I guess.

One describes "This problem occurs because the System File Checker must verify the SP2 files against the originally installed files. However, the System File Checker does not recognize the Windows XP SP2 CD or the Windows XP CD."

SYMPTOMS
When you try to run the System File Checker tool (Sfc.exe) on a Microsoft Windows XP Service Pack 2 (SP2)-based computer, you may be prompted to insert the Windows XP SP2 CD. However, the System File Checker does not
accept either the Windows XP SP2 CD or the original Windows XP CD.

Method 1: Insert a Windows XP CD that has SP2 integrated; I have that CD. They talk about 828930 (http://support.microsoft.com/kb/828930/),
"How to integrate software updates into your Windows installation source files." That method was a bit beyond me.

Method 2: Modify the registry to point to the Windows XP SP2 Setup files.

1. Click Start, click Run, type regedit in the Open box, and then click OK.
2. Locate the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Setup
3. In the right pane, right-click ServicePackSourcePath, click Modify, type %windir%\ServicePackFiles, and then click OK.

Tried that, changed it from E:\, to the above. No luck. Well, SourcePath in registry in same group down just a bit farther also says E:\. I even tried to set it to a local DIR., where I'd copied the CD to today, also with no luck.

The ServicePackCachePath line reads c:\windows\ServicePackFiles\ServicePackCache,
tho' I can find no DIR by that name, unless it's hidden. (?)

At this point, I gave up; came here for help, again; ideas, anyone, please?