Using 64-bit product code to upgrade to 32-bit

I've been running the RC for a few months and it runs out in the next few days. I bought a Windows 7 disc but was sent a 64-bit disc instead of 32-bit and now cannot return it as the package has been opened. My computer won't even run the setup because it doesn't support 64-bit. Is there any way I can upgrade to 32-bit using the 64-bit product code?

LiveCursor said:

I've been running the RC for a few months and it runs out in the next few days. I bought a Windows 7 disc but was sent a 64-bit disc instead of 32-bit and now cannot return it as the package has been opened. My computer won't even run the setup because it doesn't support 64-bit. Is there any way I can upgrade to 32-bit using the 64-bit product code?

EDIT Thanks Kari

As far as I know, with one key you can activate either 32-bit or 64-bit Seven. I mean, a normal retail pack comes with both disks but only one key. it's then up yo customer to decide which version to install and activate with that key.