Hi Ruth,
Migration from 32 bit machine to 64 bit machine and from SQL 2005 to 2008 is not a problem for SharePoint. From my opinion, I recommend you deploy a new MOSS farm and use database migration method. For the detailed steps, you can refer to Technet document below:
Chapter overview: Deploy a new farm, then migrate databases (Office SharePoint Server)
http://technet.microsoft.com/en-us/library/cc263186.aspx
Follow the instructions in this document will help achieve your goal successfully. Don’t miss or skip any steps especially the post-upgrad steps to ensure all the sites can work without problem.
http://technet.microsoft.com/en-us/library/cc263327.aspx
Hope this helps
Lu Zou
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