Ok, I've got an older-ish Dell (Dimension 4700 if that HELPS any) with SATA 1.5 capabilities, and just got a 1TB SATA 3.0 WD drive as a gift, but my BIOS doesn't recognize it. I've confirmed the drive is working (installed it on my boyfriend's much better, much newer MACHINE with no problems) and I know all my cables and slots are working (have another SATA 1.5 drive installed where I was going to put the new one). So all my research so far points to the fact that my BIOS just isn't able to support the newer SATA 3.0 - even though in most CASES it is backwards compatible, it would appear I have one of those systems that is the exception. I tried changing the jumper settings to restrict the 3.0 to 1.5 as instructed on WD's support site, but no joy. (The only option left is to call their support, which is hard because I sleep in the hours they're open...)

Considering this is a stock Dell with integrated everything on the motherboard and not much room for expansion, is there any hardware I can add that will allow me to use this drive? Motherboard & BIOS configs are not really my strong points, so I'm a little ignorant when it comes to these bits.

I've tried to answer the question myself, but I can only find info on items to buy without being able to tell if they will help me, so I'm asking the experts.
What BIOS are you currently USING ?

A07 under Fixes and Enhancements has the below statement.

Improved drive detection for new larger hard drives.

LookHere

You can install up to A10 Bios upgrade.I only noticed the A07 as having
'Improved drive detection for new larger hard drives'. So.....Try the A07.Ah yes, the simplest explanation is usually the right one... FLASHED the BIOS (to A09 in fact) and now it works!

Much appreciated, now to just get the 300GB of data copied over...  Good for you.We are glad that fixed it friend.