NEED DC VOLTAGE REQUIREMENTS FOR A WESTERN DIGITAL 1TB DRIVE, MODEL WDbaau0010hbk-01. I have several AC Adapters, some of which are 12VDC. But most drives I've seen run on +5VDC.

Yes, this model is certainly compatible with Windows 7.
If you've lost the AC adapter and need to replace it, the most important things to look at are:
1) the size of the plug
2) the input voltage of the drive
3) the minimum current in Amperes (A) or milliAmperes (mA) required

For units manufactured after June 1st 2008, these are the requirements:
12 Volts
1.5 Amps
18 Watts

Western Digital recommends only using original WD power adapters.

See here for more information: https://wdc.custhelp.com/app/answers/detail/a_id/1378/related/1/session/L2F2LzEvdGltZS8xMzg3MTQwNTQxL3NpZC9aNG1NbVZIbA%3D%3D

Tip: sometimes you can find a cheap and original power adapter on eBay or Craigslist or Kijiji.

The USB HDD driver is built in on XP. If the drive is not recognized try the following;

1. If you usually plug it into the front USB, Try the rear USB
2. Try a flash drive in the same USB and see if it works
3. Plug the HDD into the USB then look in Device Manager for it, Right Click and click Update Driver then select Windows Update for the location.

"DC to AC" cords are not really a common item. They are called "Inverters". Typical inverters are 12VDC to 120VAC and are found in mobile applications to operate houshold current type (120VAC) devices. Inverters cost many times more than thier "AC to DC" or "AC to AC" sisters.

An "AC to DC" and "AC to AC" cord however, is a very common item. They are usually called simply "AC Adapters" and are sold in many electronics stores (Best Buy, Fry's, etc.) and electronic specialty stores (Radio Shack) and electrnics suppliers (MCM, etc.) Nearly all of them are designed to reduce the voltage in your home (120 VAC volts alternating current) to a different but usually lower voltage that is either AC or DC.

In order to select the proper AC adapter, you need to know:
(1) Input Voltage - this is the outlet voltage - often 120 volts in N. America, (2) Output voltage - this is the voltage the device needs and is often indicated near the jack, The adapted must match this voltage. (3) the device voltage type - this will be either AC or DC. The adapter must match the type as they are NOT interchangeable. (4) the size and type plug on the cord that will allow it to mate properly with the jack. There are many, many types and it should be tested for fit prior to plugging in and must match the device jack (5) the power requirements - this is usually shown as a number in Watts (w) and / or Amps (a). It is very important that the apdapter power rating is equal to or greater than the amount specified by the device. Failure to meet the requirements above can cause failure of the device, adapter or both.

I hope this helps and good luck!

I don't have a photo of the AC adapter, but if you look on it the Voltage and Amperage specifications are;

Input: 100-240VAC / 50~60Hz
Output: 12VDC / 2A

This means the Input power can be from 100 volts to 240 Volts AC, and at 50 to 60 Hertz

The Output power is 12 Volts DC at no more than 2 Amp's. (Amperes)

Asian Power Devices Inc. has a model DA-24B12 that fits these specs.
Also a Wattac AC adapter model number - BAO362Zl-8-A01 will work.

Otherwise just use a 12 Volt, 2 Amp power pack, with a positive on center contact, and a 2mm pin hole

You will need a 12V, 2A tip positive power supply with that drive model.

this should help you out
Electrical Specifications: (current requirements) AC Input Voltage: 100-240 VAC AC Input Frequency: 47-63 Hz

I don't have a photo of the AC adapter, but if you look on it the Voltage and Amperage specifications are;

Input: 100-240VAC / 50~60Hz
Output: 12VDC / 2A

This means the Input power can be from 100 volts to 240 Volts AC, and at 50 to 60 Hertz

The Output power is 12 Volts DC at no more than 2 Amp's. (Amperes)

Asian Power Devices Inc. has a model DA-24B12 that fits these specs.
Also a Wattac AC adapter model number - BAO362Zl-8-A01 will work.

Otherwise just use a 12 Volt, 2 Amp power pack, with a positive on center contact, and a 2mm pin hole

first of all , you are looking at the wrong voltages. The important voltage is the DC OUTPUT, which is the voltage the external harddrives use AND the polarity of the plug attached to the harddrive end of the cable.
if both the harddrives have say 12v dc output and both have the insignia of the center conductor being + (posative) then you can interchange them. and you CAN run a 9volt unit with 12volt DC power, but not the other way around.
Look at your power adaptors again for the OUTPUT and polarity.
should be a half-circle with lines depicting the polarity(+,-) of the center and sheild connections to the hard drives printed on both the harddrives and the power adaptors . This can also be tested with a dc volt meter while the adaptors are plugged into the wall.
DO NOT try to test the AC end while plugged in!!
Regards

If you can procure it you need a "Wattac" AC adapter
model: BAO362ZI-8-A01 (made in China)

Otherwise you need a 12 volt 2 Amp. power pack with positive on centre contact & 2mm pin hole.

Try the manufacturers at 
United Kingdom
Leatherhead
Western Digital (UK) Ltd.
Prime House
Challenge Court
Barnett Wood Lane
UK-Leatherhead, Surrey, KT22 7DE
Phone: +44.1372.36.0055
FAX: +44.1372.36.0389