The Dell enclusure I belive was designed by flextronics........
On the older Dimension XPS seiries the case was based on the
Palo Alto ATCX as reviewed by Anandtech .Palo Alto Products has since been brought by Flextronics..
The current black Dimension cases don't take full sized ATX boards anymore....
1.I think it has only 5 brackets now...so it can only take shortened Motherboards Only.....!!! (ie Micro ATX)...
2.You will also have to change the PSU...Think dell still uses some funny PSU so you are going to have to change it..
3.Also with the front pannel connectors...you will need to wire them your self again..(tip a CD-rom Audio Cable to rewire it)
4.You will also need there drive rails if you want to add new parts... (think you can call them up to get the parts)..
5.They are damm quiet...
6. Yes you can mount standard CPU cooler in that case...but not with their mobos.
7. Dell uses 92mm fan for their CASE/CPU which aren't that readily availible...The one they use are damm quiet thou..
Lookin at the current dell case, you can see that it was optimized for mass assembly.... I they can slap all the compnents in the assembly plant in less than 1 min.......Thats why they can offer the (component) customization which other vendors have difficulty offering...
So if you want to use one of the newer clam shell you will need to put a little work into it....