Yes, it is possible to mix landscape and portrait pages in one Excel 2007 worksheet. Here are the steps to achieve this:

1. Open the Excel worksheet and select the first 8 pages that need to be in portrait mode.
2. Click on the "Page Layout" tab in the ribbon at the top of the screen.
3. Click on the "Orientation" button in the "Page Setup" group and select "Portrait".
4. Set the column widths for these pages as desired.
5. Next, select pages 9 and 10 that need to be in landscape mode.
6. Click on the "Page Layout" tab in the ribbon at the top of the screen.
7. Click on the "Orientation" button in the "Page Setup" group and select "Landscape".
8. Set the column widths for these pages as desired.
9. If you want to adjust the margins for any of the pages, click on the "Margins" button in the "Page Setup" group and select the desired margin settings.
10. Finally, if you want to preview how the pages will look when printed, click on the "Print Preview" button in the "Workbook Views" group on the "View" tab.

That's it! You should now have a worksheet with a mix of portrait and landscape pages with different column widths as needed.