Power steering fluid leaking and there is a whining noise along with a rattling sound on my 2000 Nissan Maxima.

SOURCE: Power steering leak --a lot

Three areas of concern. A leaking steering rack: By looking under the car, look for the rods which tie the left and right wheels together in the center. By turning the steering wheel fully to the left or right, you can look behind the front wheels 1/2 way down and you will see the rod I am referring to. Following the rod to it source of attachment, it will have a rubber bellows type cover surrounding is as it gets near the center of the car. If the rubber is torn and has oily residue, that is where you are loosing your power steering fluid. It is a leaking power steering rack. A fairly expensive repair, best left to a professional. Buying a used one is a real crapshoot because they are very prone to failure as they get older.
2. The high pressure hoses will leak on these cars. It is difficult to see these without putting the car on a lift because the pump is on the firewall side of the engine. If you notice the fluid dripping near the pump, it is a higher probability than not that it is the high pressure hose than the pump. Also look at the return hose coming from the reservoir, Sometimes the clamps aren't that tight and it will cause a leak, but your description sounds like a leak under pressure.

SOURCE: 2002 Nissan Maxima "Clicking-Rattle" noise from under hood

Exhaust leak?

SOURCE: Power Steering Fluid

sometimes adding brake fluid to the power steering pump will stop the leak if its not to bad.you may have to keep adding as it leaks down untill you use about a bottle ,before it stops the leak.

SOURCE: my nissan maxima 2000 does not have any power

Check your MAF out. If your revs are slow and you lose power top end it could be faulty.

SOURCE: 2005 nissan altima power steering fluid is fine and no leaks but

could be the pump pressure has deminished or blockages within the steering rack! [valves]
cheers Rob