Answer
ESRI recomends upgrading to an 8.1 license manager and license file. Use the existing hardware key.
The 8.0.x license files will unlock ArcInfo 8.1, ArcSDE 8.1, Spatial Analyst (if previously licensed for GRID), 3D Analyst (if previously licensed for TIN), ArcPress and the existing ArcInfo Workstation extensions.
However, ArcEditor, ArcView (Floating), Geostatistical Analyst and Streetmap USA extensions require an 8.1 license file that contains these additional features.