You need to download the bootcamp 3.1 driver upgrade from the Apple website. You can get the 32-bit update here: http://support.apple.com/kb/DL996
Edit: I have found that WinXP boots over 30 seconds faster than Win7 on my Mini.About Boot Camp Software Update 3.1 for Windows 32 bit
This update adds support for Microsoft Windows 7 (Home Premium, Professional, and Ultimate), addresses issues with the Apple trackpad, turns off the red digital audio port LED on laptop computers when it is not being used, and supports the Apple wireless keyboard and Apple Magic mouse.
This update is highly recommended for all Boot Camp 3.0 users.