I wouldn't recommend it, considering that Dells built from late 1998 onward use a main ATX connector which fits into a standard ATX motherboard's receptacle, but has non-standard pinout. If you try this, get a new power supply too.
Also check to see if the case's front wiring is in a single big connector built specifically for the Dell motherboard, and consider whether you want to work around that. It can be done but people sometimes get intimidated by the need to get creative with 'em.