Please take a look:

Windows 7 and Boot Camp: 01/20/2010
Boot Camp Software Update 3.1 for Windows 32 bit
http://support.apple.com/kb/DL996

Boot Camp Software Update 3.1 for Windows 64 bit
http://support.apple.com/kb/DL979


Use the Boot Camp Utility for Windows 7 Upgrade Installation Utility before upgrading from Vista to Windows 7.
This utility safely unmounts the read-only Macintosh volume on Microsoft Vista.
http://support.apple.com/kb/TS3172

Important about iMac ~ 2006
http://support.apple.com/kb/HT3986