Hello katva,

Folder:
C:/Documentsand Settings/AllUsers/ApplicationData/AVG10
actually belongs to AVG 2011 and is needed for AVG to work properly.
Previous version of AVG was AVG9, there was no AVG 2010.

It is safe to delete update subfolder:
C:/Documentsand Settings/AllUsers/ApplicationData/AVG10/update/

It will be automatically recreated during next AVG update.

Thank you