As Merlincustom mentioned you may want to check a few things to ensure you are indeed replacing the correct/worn part?
Depending on wear and tear and related life/age of parts/fittings the drivetrain noise could come from a worn and damaged chain, check links for cracking and measure chain wear as explained here
http://forums.veloreviews.com/viewtopic.php?f=90&t=970
I always check the chain ring bolts first for tension as when they are loose or very dry they will creak, don't ask me how I know about that one, except to say I basically stripped and rebuilt a bike before isolating the noise to the damn chain ring bolts
You might also want to check your pedals are greased on the threads and tightened firmly. Check the bottom bracket is spinning free and with no sideways freeplay by dropping the front gears to the small chain ring, then remove the chain from off the small chain ring and if possible let it rest on the bottom bracket shell, then you should be able to turn the cranks with no restriction from the chain, this isolates any noise and if the bottom bracket is indeed shot you should feel a firm or very rough bearing.
The cups of the bottom bracket could be loose in the frame which will cause them to creak under load. You would need to remove the crankset to check the bottom bracket cups are tight.
Another area noise can come from and sound like your cranks is from the removable rear derailleur hanger/tip mount. If the rear hanger/tip is loose or very dry where it mounts to the frame, clean, grease and re-tighten to the frame.
While you are there make sure the cassette is tight on the rear wheel hub as they will creak and moan if not tightened enough.
That should keep you busy for a while and I hope it helps you find the problem
Good luck
Shane
