There are probably already lot of posts on the installation of the Oracle client, so this is a small note;
If you start visual studio on a machine that hasn’t got the Oracle 32-bit client installed, prepare to face the following error;
‘The following assemblies are installed SDK assemblies but could not be shown in the customize toolkit dialog because they…..’
This is because VS.Net is 32 bit and you only installed the 64-bit Oracle client.
Install for your DEVELOPMENT environment both the 32-bit and 64-bit client.