This is for a laptop?
If so, you have to disable your battery detector, because dell has a lovely feature where the laptop will not charge if it is not using a Dell Certified PS..
I am trying to remember how to do so.
As far as getting a new one, you can buy one from anywhere; it doesn't have to be Dell Certified.
Oh I see this is for an actual PSU for a desktop...
Well, looking at it
It is much differently shaped than any of the normal sized PSU's so you might have to get the Dell one...I'm not sure, soz :P