First you have to know most of Dell use the other format motherborad/case that is btx.
When you look at the manaul from Dell, you can see the the front panel mobo connectors (7 and 8) is totall difference between this and regular one.
http://support.dell.com/support/edocs/systems/insp62062...
So 1) keep your dell or 2) buy the new MB/case, maybe the PSU too and use the CPU, RAM, and DVD, etc.