The Recovery partition on Dell is volatile when it's hotlinked to the F8 Advanced Boot Tools menu and doesn't re-appear after a Clean Reinstall, so trying to impose GRUB on the HD might affect it. Save a Win7 backup image of the entire HD if you're concerned about it and make your Recovery disks if available:
Dell Windows 7 PC Restore
Dell Recovery Partition - restoring F8 link
I do not see the standard Dell OEM bootable diagnostics partition. Did you delete it? Try booting it now to see:
Dell Diagnostics Utility - How to Run the
To minimize the impact use these steps to
Dual Boot - Windows 7 and Linux - Windows 7 Forums
But most tech enthusiasts wouldn't run the Dell factory preisntall of Win7 anyway, since it's loaded with bloatware and duplicate utilties with better versions built into Win7, which throttle and corrupt the best OS ever. So I would consider first doing a
Clean Reinstall - Factory OEM Windows 7 during which you delete all partitions, then after setup save a Win7 backup image to use in place of Recovery.
or at the minimum I'd
Clean Up Factory Bloatware.