SATA drive not detected

Recently bought a 750Gb WD external drive which boasts USB, FW and e-sata connections. Of course it has its own power supply.
So I bought an e-sata slotplate with a rear cable that's plugged in the remaining free sata socket (the other one is used by my SP1650 Samsung drive).
Using Windows XP Pro.
The motherboard is Asus P4C800E, latest bios.

Problem is nor in the Asus bootsetup nor in Windows anything shows up.
Thought sata is supposed to be hot pluggable?
Do I have to add the drive somehow?
I thought e-sata and sata only differs in connector type, which hurdle I neatly skipped (I thought...).
The WD is working fine through usb and iee1394 (firewire).

Do you happen to have the correct drivers installed for your SATA controllers?

Yes of course, the first SATA socket is working fine with the built in harddrive.

The drive is designed for SATA II, i.e 300MB/s.

Does your motherboard support 300MB/s?

If NOT make sure the jumper on the hard drive is set to limit the drive to 150MB/s?

Thanks, will try.
But how do I open the "book" ?
There's nothing in the manual about setting jumpers or opening the case...it's the rounded case with slits and tiny holes all over the top, bottom and rear.
It's a WD Mybook 2 Studio Edition; I already formatted it for Windows by connecting through usb.
BTW- after that the PC hangs at boot, listing 4 usb devices and hanging at #5 which is probably this book...

Broke the thing apart (terrifying!) and set the 5-6 jumper, no change.
Called WD and they insist it cannot work, esata is NOT compatible with sata, it's a different protocol.
Are they correct ?
I thought the only difference was the connector and some minor level changes because of the longer cables?
BTW- usb is working fine even after my tampering
Took out the Asus P4C800E De Luxe mobo's CD and installed sata via the quaint oldfashioned inf file, no change.
Not seen in the bios, and consequently not in Windows.