P.S. It may also need to be partitioned and formatted, but you can't do that until it is recognised. For Gods sake don't use fdisk to do that as fdisk automatically goes for C:

If you don't have access to Partition magic or similar, then temporarily instal the new HD as primary master and use a startup disk to fdisk it, then return to the layout above and format. Formatting isn't a problem with a new HD, as you can't lose data if there isn't any.

Don T.