Previously installed .Net Framework 3 not acknowledged by WU websi

I keep a local cache of the following updates on a networked PC so that
whenever I rebuild a system I can install these over the LAN rather than
downloading them yet again:

IE7-WindowsXP-x86-enu.exe
wmp11-windowsxp-x86-enu.exe
dotnetfx _v1p1.exe
NDP1.1sp1-KB867460-X86.exe
NDP1.1sp1-KB928366-X86.exe
dotnetfx_v2p0.exe
NDP20-KB922770-X86.exe
NDP20-KB928365-X86.exe
dotnetfx3.exe

The problem is that the Windows Update website does not detect .Net
Framework 3 is already installed on the system. It _does_ detect that each of
the other updates are installed. So this behaviour appears to be unique to
..Net Framework 3.

Has anybody else noticed this behaviour?
Is there a remedy other than checking:
[x]Don't show this update again