After doing more research, it appears that the NAS IS actually that slow in RAID 5. It has a “fast” 500Mhz processor running Linux, but uses a software-based RAID. In comparison with other RAID NASes, 7MB a second is actually pretty good for write speed.
Now I have to figure out if I want to keep the damn thing… it’s more than adequate for streaming media (even HD media), but large file copies is PAINFUL… dumping 300GB of MP3s to the thing takes many many hours.