Well, this has happened to me once and I made a decision. The drive was a little older, external 1394 CD-RW. I wanted to swap it out of the bay and place a faster one in. The new one didn't work at all and the original.....well, let's just say the same situation was my end result.
I had been using it for about 2 years so if there was still a warranty (doubtful) than I had voided it by taking it apart. But, I ended up posting it up on eBay really cheap and got about half of what I originally paid. I was honest about my eBay listing and figured that someone out there would know exactly how to fix it and use it again. I know that this recommends considering this a loss. I wish I could help you further but (looking at your system specs) I would hate for you to damage the new drive even further, ya know?
It could be as simple as a power lead. In fact, you may be able to seach google.com for a hardware spec to walk you through the hardware and just run a quick comparission.
Hope you figure it out....Good Luck!