To speed up you restore times, try offloading all your larger and personal files (music, photos, documents, virtual machines, etc.) to a separate partition, but still let Windows back up both partitions. By doing so, you'll keep the system image size much lower and reduce image restore times for your system partition immensely. In case of an emergency, you can the system image (Windows, your applications, your user account data) and get back to work faster. Your D: drive should still be there -- and even if that's messed up, you've still got an image you can mount. To do so, use the Diskmgmt.msc command to launch Disk Management, go to Action -> Attach VHD, and select the secondary partition from within the image folder \Windows Image Backup\PC_NAME\Backup Date -- it'll be the one with the higher string number in the file name.
Keep the Windows DVD or a recovery CD with you
If Windows detects boot problems, it usually automatically runs the Windows Recovery Environment (or WinRE -- we'll discuss this in more detail below) and presents you with options to restore an image or perform various repair commands. However, if your hard disk is really screwed up for whatever reason, it might even affect the hidden recovery partition that contains WinRE. If you're using Windows 7 or Vista, in such situations you can use the Windows DVD, or the recovery CD that Windows backup creates right after it's finished creating your image. You can burn such a recovery disc any time by going to Control Panel -> System and Security -> Backup and Restore -> Create a system repair disc. You can also put WinRE on a bootable thumb drive.
Restoring an image works in most cases, but it takes its time (even with the strategy mentioned above) and effectively destroys all data or settings created after you've set it up. It's a last resort.