Hi Arco,
I just downloaded and installed Visual WebGui Express Studio NET4.0 .NETHTML5 / JQT Beta3 (without sources) and then downloaded and installed Catalog sample NET4.0 .NETHTML5/JQT Beta3 and I can open the Catalog solution just fine and I can see no entries in web.config that relate to any Gizmox 2.0.5701.0 assembly.
The references to the project are all runtime version v4.0.30319 / version 4.0.5701.0, so I am unable to reproduce this problem.
If you have web.config entries statiing Gizmox assemblies as v2.0.5701.0, then it looks like you have installed a NET2.0 version of the Catalog sample. I suggest that you uninstall and then redownload and see where that takes you.
Palli