fvamazon and CPU

But is it actually slowing anything down?  It has a priority of 20 (niceness of 0) and will relinquish that CPU use to a higher priority task (which will have a lower priority value in TOP).  20 is the default, neutral priority.  The kernal tasks generally have priorities of 0 and readynasd has a priority of 19, so they will take precedence.

Have you been using the Amazon drive capability long?  I've not used it, but I would not be surprised that it takes a lot of processing and/or a long time to perform an initial synchronization.  You may want to see if it calms down over time.

Unless you will have multiple users and/or multiple plex transcodes or similar applications running, a quad processor is likely overkill.  It will run a bit hot, as the NAS is not rated to it's TDP.  I generally recommend the Core 2 E7500 to be the best bang for the buck for the average user.  Jumping to its 2.93GHz is quite an improvement over the CPU in the original Pro BE and Pioneer like you have.  It's not generally worth it for the Pentium E5400 @2.60GHz in the Pro6 and Ultra6Plus units. 

Upgrading RAM to at least 2GB, with 4GB being better, can also help speed things up, though maybe not for the specific case of fvamazon.  The 4GB sticks that the NAS can support for 8GB total are a bit expensive for the gain for most users.