The license is good for either architecture.  You will, however, need to procure a copy of the 32-bit installation media.  Dell will not supply this to you (even at a cost), as you did not order a 32-bit OS.  You can use any other Dell-branded Windows 7 DVD (that matches your version - Home Premium, Professional, etc.), or you can install using Retail media (although it may take a 2 minute phone call to Microsoft to activate).
My new computer came with 64bit Win7. For various reasons (software and hardware), this doesn't work for me and I need 32 bit. Any advice on the simplest and cheapest way of doing this? As I already have a license can Dell supply me with a 32bit disc? L
Have 64bit, need 32 bit