If you want to dual boot Ubuntu 12.04 (Prtecise Pangolin) with Windows 7 (64-bit) using Wubi, this latter will automatically download the amd64 version of Ubuntu. In this tutorial, we will help you force Wubi to download the i386/32-bit version of Ubuntu using simple instructions.
You can download Wubi installer from here. Open the folder containing the EXE file of Wubi, right-click it and select "Create shortcut":
Right-click now the Wubi shortcut and Select Properties:
Under the Shortcut tab, modify the target to be like this:
Click OK to confirm the new changes. Double click now the Wubi shortcut and enter Ubuntu installation details, then click Install. Wubi will now be forced to download the 32-bit version of Ubuntu: