upgrade english sql express 2005 to spanish sql standar 2008

Hello.

I've bought a license of sql standar 2008.

When I added the license at Microsoft Volume Licensing Service center I chosed the spanish version because the SO was in Spanish.

But I didn't know that there was an old slq 2005 express in Englis installed in the same server where i want to install the new one.

Now, when I try to upgrade, the assistant says that it's impossible because the previous version is in english and the new version is in spanish.

It's possible to change the language of sql at Microsoft Volume Licensing Service and download the english version?

Can I change the languaje of the installed sql express to spanish?

What can I do?

Thanks