Hey guys I recently installed an SSD into my system and installed Windows 7. My other HDD also has Windows 7 installed but I want to set my SSD as the main drive and then reformat the other one. I changed the boot order in the BIOS to the SSD but when the system boots it then asks me for a proper boot device as if no OS is installed. However if I have the old drive set as default I have the option to pick my SSD to boot from or the old drive.
You cannot have two system drives in the same PC. The BIOS sees both of them and then cannot choose between them. Here is how you do it.
Assuming you have the data you want of the HDD unplug the SSD. Use the Win 7 installation DVD and when it gets to the part where you set up the drive choose advanced options and delete the HDD partition. Exit the set up and shut down. Plug the SSD back in. You now have one boot drive. All should be good. Start Win 7 go to disk manager and initialise and format the drive.
If you want data off the HDD to go to the SSD then put the HDD in an external esata dock of some description and get the data that way. Then format the drive.
I disagree _slightly_ with Wamphryi, perhaps because I have three bootable drives in the same PC. But Wamphyri's instructions will fix your problem; I just think that you don't have to go quite that far. Please bear with the rest of this; it may get long as I try to explain clearly.
Your SSD is not bootable; only the older drive is bootable. This is because the older drive was attached to the system when you installed Win7 to the newer drive. The Windows installation procedure saw a bootable drive and used it for the MBR and boot loader. Once the low-level boot starts on the old drive, it hands control over to the Win7 installation on the new drive.
There are two solutions. Both involve disconnecting your other drive from the system, although I would not go so far as to make it external. One is to do a Repair Install from the Win7 DVD, which will see that you have a Win7 installation but no boot loader and build one for you on the only drive, the SSD. A better one is to, as Wamphryi wrote, wipe the drive and re-install to it, which will, among other things, create the 100MB invisible boot and repair partition.
If you do a complete reinstall, you can do the SSD a favor by resetting it to factory default with a Secure Erase. This can be done from the bootable Parted Magic distro. It has the same effect as issuing a TRIM command for the whole drive.
Please be sure that your motherboard controller is in AHCI mode. If it is not, and you choose to do a repair, you may have to do a registry tweak and then change the controller mode.
That done, if you take my advice the old drive will still be internal, and you have to choose which one to boot from. This can be done in the BIOS. However, it has been my experience that attaching or removing drives, even USB drives, can cause the boot sequence to be reset. I solved that problem by attaching my SSD to SATA port number 1. Every time the boot sequence is reset, it picks that one by default.
You could also use a disk utility to remove the mark on the HDD that indicates that it is bootable. I recommend backing up a drive before fiddling with any disk utility. If you do that and delete the "program files" and "windows" directory trees, you don't absolutely have to reformat the drive.