Your MBR's screwed up. Unfortunately, EasyBCD isn't as foolproof as many would like to think.
Let's try the easy way first:
Boot into your Vista DVD, and try a Repair. It should detect two installations of Windows. Make sure you select the one on your D: drive (if they have identical names, select the second one).
Then, click on Startup Repair, and follow any instructions. After it's done, reboot normally (don't reboot into the DVD).
If that doesn't work, try it again, but select the system on C:.
If that doesn't do it, it means editing the MBR in Command Prompt, where it gets a little tricky.