as i understand correctly, there are two levels of licenceskeys for sharerpoint. For example to use powerpivit you need an advanced user licences. Does this also apply to webparts? or can the standard licences be used?
You don't even need a sharepoint license. Support for web parts is included in both WSS 3.0 and Sharepoint Foundation 2010 which can be downloaded and installed free of charge. So yes, standard license for Sharepoint is more than enough, enterprise lic is not required.