KB909520 is considered not installed by Windows Update.
"Windows-KB909520-v1.000-x86-ENU.exe" is in HF (confirmed by ERROR_REPORT.TXT)
"basecsp.cat" is in SOURCESS\I386\SVCPACK
"basecsp.CAT" is referred to in SVCPACK.INF
HFNETCHK doesn't see a problem (at least not with this update).