In Windows Vista and Windows 7, you do not need to use an OEM disk to install windows, as long as you have the valid activation key on your certificate of authenticity (COA, the sticker on your laptop with the license key).
Automatic activation is achieved by a special encrypted file on the disk which the OS verifies against a code stored on the motherboard. If they match, then the OS knows that your computer was by the manufacturer that the OEM Windows disk is from, so it doesn't even ask you for a key.
If you don't have an OEM disk, you can still install Windows using a retail, upgrade, or MSDN/TechNet disk, as long as it is the same edition of Windows (Home Premium/Business/Ultimate). It does not matter if it is the same architecture (64 bit vs. 32 bit) or even laguange edition.
What will happen if you use a non-OEM disk or a disk from a different OEM is that automatic activation will fail, and you will be prompted to enter a product key. Enter the product key from the sticker on your computer. Because OEM activation is usually automatic, and one rarely needs to use the product key on their computer, you will have to call the Microsoft activation hotline to complete the installation. You read off a code generated by the computer, which allows them to determine if the computer is properly licensed, and if it matches, then they read back a code which you enter, allowing the activation to proceed. If this process doesn't work automatically, you can speak to a live person and ask them to help you; as long as you are legally licensed, they should be able to get you up and running.
I've done this all before, I know it works and Microsoft is very helpful with it.