Lists in Windows SharePoint Services can only contain a certain number of fields or columns. If a list in your site contains too many fields or columns, it are not migrated. You must manually re-create the list. Note that this includes surveys. The maximum numbers for fields and columns are:
- 64 text fields, including the following field types: Single line of text, Choice, Hyperlink, or Picture.
- 16 Lookup fields
- 16 Date and Time fields
- 16 Yes/No fields
- 32 Number and Currency fields
- 32 Multiple lines of text fields
In MOSS2007/WSSv3 these limitations are gone. The only limitations is the performance of your list: Sharepoint 2007 - Column Limits