Your upgrade is blocked because the existing component is a later version than the version you are trying to upgrade to. To modify an existing SQL Server component, go to Add or Remove Programs in Control Panel, select the component you would like to modify, and then click Change/Remove.
This is in regards to installing advanced services for SQL Server 2005 Express using the skuupgrade=1 tag. I have removed all .net service packs, but I cannot get through the install. What else would be causing the existing installation to be more recent?