Can you provide a bit more info, is this a new build or an upgrade, is the drive new and being fitted as a 2nd drive for data only.
If the HDD is new then it will need to be formatted and a drive letter allocated to it + if it it is to be the main or only HDD then it needs to formatted and a seperate partition created for the OS, what OS are you using by the way.
Below is some info I found for you;
Troubleshooting hard drive installation
If your drive does not show up in the POST screens when you boot your computer, and does not appear to be present in your Windows installation (if you have one), or cannot be found by the operating system when you install Windows, the first thing to do is power off the computer and recheck all jumper settings and cable connections as detailed at the beginning of the guide.
Note that SATA drives may not appear at all in the BIOS depending on the manufacturer of the motherboard and the way that SATA support is implemented, even if they are installed correctly. This doesn't mean that they won't work, just that you can't confirm their existance without using Windows. There's nothing you can really do except proceed with booting or installing Windows.
If your drive appears in the BIOS and Windows, but is missing a significant amount of space (say you are seeing 20GB instead of 40) you are probably being limited by your motherboard. Older motherboards can be limited in the amount of hard drive space that they can 'see,' so if you attach a drive that is over the limit of the board, you will likely get only a portion of the actual space of the drive visible in your BIOS screen. Sometimes, a BIOS update to the motherboard will also help this situation, but as older motherboards are not always supported there may simply not be a BIOS update work around.
To work around this problem you will need to go to the drive manufacturer's website to download an installation utility. Every hard drive manufacturer has a version of this available. Maxtor's Maxblast3 software is one example.
Their purpose is to enable older mainboards with a built in HD space limitation to overcome this. As this software will also partition and format the drives for you, it can be quite useful. There are too many versions of this type of software to detail them all here, but they do come with instructions for use. If you do end up using the drive manufacturer's software, we would recommend that you also use it to partition and format the drives if possible, unless you are performing a new installation of Windows 2000 or XP.