You might need to update your BIOS to recognise the new drive. There are a couple of ways to get round it, if you don't fancy doing that and personally I wouldn't advise you to update the BIOS, it can be dangerous if you don't know how to do it properly. Most drive manufacturers will have a software solution you can use to get your drive recognised, a Drive Overlay, I think they call it, I used one last week but can't remember the exact name of it. Another way to get your computer to recognise your new drive is to use a PCI controller card. This slots into one of your PCI slots and allows you to connect other CD/Drive devices.