following installation into the tower, this new drive doesn't appear under computer managment. I'm installing this on a 2006 dell dimension which came with a Pentium 4ht processor 2.8GHz and 1GB of RAM. Do you see a reason as to why my WD HD isn't being picked up?
(sata and power cables have been tripple checked)
Check exactly where in Computer Management you are looking. A new empty HDD will only show up in ONE place. Go to Disk Management. Look in its LOWER RIGHT pane. It SCROLLS so you can see all the hardware storage devices in the system, even those Windows does not yet understand. Your new HDD should be there showing all its space as Unallocated Space. It will NOT show in the Upper Right pane.
You need to RIGHT-Click on that space and choose to Create a Partition there. (You can choose to Create more than one Partition if you need to, but I'm going to assume you want ALL of the new drive as ONE drive.) Set its size (all of the HDD, if that's your choice). IF you do NOT plan to boot from this drive (that is, you only plan to use it for data storage, etc.) do not make it bootable. However, if there's any choice, this first Partition on your HDD should be a Primary Partition. Now the Formatting options. If you are running a recent OS like Win XP SP3 or later, you should see choices like File System and Full or Quick Format. Choose the NTFS file system unless you know you need something else. A Quick Format will do the whole job in about 15 minutes. A Full Format does that, and then exhaustively checks the entire disk for bad sectors, marking off any so they are never used and never cause a problem. This is a multi-hour job, so if you choose that option, be patient. It may not be necessary on a new HDD, but it's a reasonable precaution if you have the time. When the whole job is done, back out of Disk Management and reboot so Windows can adjust its registry, and your HDD will show up in My Computer.
IF you are running an older OS, it is possible you won't see any Format options where you set up choices for the Partition creation. In that case, let it do the Create Partition step (does not take long), then RIGHT-Click on the resulting Partition and choose to Format it. Make your choices as above and run this as a second step, then back out and reboot.