I have a new PowerEdge T320. Details are:

* Intel Xeon E5-1410 @ 2.8 GHz
* 16GB
* Windows Server 2008 r2 configured as Domain Controller
* Dell PERC S110 Software Raid
* 4x 7200 rpm 1TB drives configured in Raid5

Clients initially started complaining about Quickbooks getting disconnected. In troubleshooting, I found that I am getting what I see as a terribly slow read speed on my hard drive. 

HDTune, Dskspeed and ATTO all show about 5MB/s read speed. ATTO showed up to 15MB/s when reading 1024 blocks. 

I have one Dell support agent telling me "you shouldn't use software raid" and another telling me, "this is not that bad".

So, my questions:

1. Does a read speed that slow indicate a problem with one of my drives, or is it to be expected with software raid?
2. If it is a symptom of a problem, is it possible that it would cause an application like Quickbooks to fail pulling data from server and, as a result, stop responding.
3. Is there a way to pull out a drive from server, test the read write speed on another machine, and reconnect it without rebuilding the drive?