found this on spiceworks
"I finally got it to work. I've concluded that the instant client downloads don't work for Win2k8 R2. The following worked:
download the full client for oracle 126.96.36.199.0 for 64 bit windows and install
download the full client for oracle 188.8.131.52.0 for 32 bit windows and install
Use the odbc administrator in the syswow64 directory to create a DSN pointing to oracle.