20 Watts per drive. These old iron machines do lose power supply capacity as time passes so I'm going to agree with you.
Also, are you doing the following (watch the video) yearly?
runninig xp with igb ram about 4 years old, using 2 internal hard drives c and f , 80gig and 120 gig ,c drive for windows and docs ect, f drive for everything else, recently pc would not boot up, removed the f/d then it reboots ,tried the f/d in my other pc and it worked, could it be a low power supply? like not able to run the 2 drives, if anyone out there could help me out would be very greatfull thanks. (the jet)