Disk Management is NOT Device Manager - it is an entirely different tool. It is where you go to Partition and Format any new drive so it can be used by Windows. It is also where you should be able to get helpful info on your "missing" drive.
jsrudd told you one way to get there. Here's another. Click on Start lower left, and in the main menu RIGHT-click on My Computer. From the mini-menu choose Manage, and this pops up a new window. In the left pane expand Storage if necessary and click on Disk Management. You will see two panes on the right - BOTH are scrolling so you can move through all their contents. The upper one shows you all the drives Windows is using now. The LOWER RIGHT pane has a series of horizontal blocks, one for each hardware device in your system. For example, I expect the first one represents your Velociraptor unit and it has a small sub-box on its left end that says "DISK_0" with its size and a few other details. To the right of that will be one large block representing the Partition on that unit that is being used as your C: drive, with its name, size, and a few other items. There will be another block below representing your optical drive.
If things are working, you should have two more blocks - one for the new Blue which will show all its space as "Unallocated Space" because you have done nothing with it yet, and another block representing the black unit. From here you can Create and Format Partitions (each will be labeled and used as a unique "drive") on any of the drive units. But before you do, plan: you will create Partition(s) on the Velociraptor, but do you want them to have letter names right after the ones you have now, or do you want the older used black drive with its Partitions to have the next names, and then the new drive comes after? If you want the raptor to be last, let's try to fix the black unit first.
Is there a block representing the used older black unit? If not, then it is completely unrecognized. You will have to look closely in the BIOS Setup screens for info on that. Maybe it is plugged into a SATA port that is not yet Enabled. Or maybe its SATA mode is set wrong - easiest option to manage is IDE (or PATA) Emulation mode. If necessary, configure options in the BIOS to get the older drive recognized by the mobo and BIOS, then come back to Windows Disk Management and verify it does show up in the lower right pane.
OK, so the black unit is there now. I'm assuming it is NOT showing yet in the upper right pane with a letter name - if it is, then you must have fixed something, and it should be visible in My Computer and in Device Manager. But if it is visible only in the lower right pane of Disk Management, check the large block representing the Partition that exists on it. Does it have a letter name? If not, RIGHT-click on that block and choose the option to Change or give it a letter name - any letter not already in use. If you need to do this and can, then simply exit out after making the assignment and reboot so Windows can recognize that drive, and it will show up in My Computer.
If these steps don't allow you to get the black unit working, report here what it actually does say in the blocks representing the black unit. Maybe that will give us clues to help you.
Now, on to the new Velociraptor. It has one large block of Unallocated Space. Decide whether you are going to Partition it into one large volume using all the available space, or into two or more smaller Partitions. There's a two-step process to go through, although some Windows versions will pop up a Wizard to combine the two and make it easy. RIGHT-click on the Unallocated Space and choose to Create a Partition. Make it a Primary Partition. Set its size. Since this unit will be used for data and not as a boot device, it does NOT need to be bootable. If there are no options about Formatting and File Systems here, we'll do that as a separate second step; hence, just run the routine to create the Partition. Once that is done, the display will change and the block will be a Partition instead of Unallocated Space. RIGHT-click on that again and choose to Format this Partition. (As I said, this step MAY be included in a Wizard.) Choose the NTFS File System. A Quick Format will do all you need in 10 to 15 minutes. A Full Format will do that, then take MANY HOURS to do extensive testing on the entire disk surface looking for bad sectors to mark off. The long way is not usually necessary with a new disk, but it's a precaution that only takes time and patience. Your choice. When it's done both these steps it will have assigned a drive letter to it. If you want to for any reason, you can RIGHT-click again on that new drive and Change its name to another letter. When done, exit out of Disk Management and reboot. The drives should all be in My Computer ready to use.