raid on optiplex 745

I purchased a Dell to have a raid system after my old system died.

 

long story short, two 160 gig sata drives which I wanted to mirror each other. the system arrived, all is well. I called Dell tech support to see if or what I need to do.. they said nothing.

 

now D drive is not mirrored to C drive. I have a working system on C and an external drive , but D drive is not mirrored, I am not a Raid guru by any means. I assumed it would mirror automatically.

how can I get the D drive to mirror C without having to uninstall windows and start from scratch?

If I am hearing Dell tech support properly, the system was not configured properly, "Raid should have been enabled" type probing questions.. scary to me.. I do not want to have to reinvent the wheel again.

 

I was going to order mirrorfolder software to mirror my system, but they tell me the motherboard should do this and not need their software. but when I call Dell, so far I've not gotten that warm fussy feeling of they know what they sell or support?