this is different about what I see in dell software Toad specification that if When running on a 64-bit operating system, you must use the 32-bit Oracle Client. and Only the 32-bit Oracle client is supported.
A 64 bit operating system can support both 32 bit and 64 bit applications. A 32 bit operating system can only support 32 bit applications. This is true for ALL applications, not just Toad.
The key for Toad is that your Toad bits and Oracle bits have to match. If you have a 64 bit OS, you can run either 32 bit or 64 bit Toad as long as you have a matching Oracle client. Your choice.