Hey does anyone know what kind of case that dell usues on their Dimension's. if so where can i get them.. thanks

I saw this on a post at anandtech.com...The case is by the people that make the case for Dell...but it's their own personal design. The insided remains the same.
http://www.anandtech.com/showdoc.html?i=994

If that link doesn't work, then go to Anandtech's reviews, then cases, then go down to the Palo Alto
They're made by Palo Alto(incidentally they also make the palm pilot cases)

Also...not to dissuade you(well..maybe I am), but there are a lot of cases out there that look good on the website, but turn out to be crap(especially my ebay-bought case). Be careful.

If I may make a recomendation,
A-top 900 or 901(traditional grey, or black) at www.pccase.com

This case(the 901) has not only been my baby, but I've gotten a lot of praise from the Computer Science guys at my residence hall.

It's not very expensive...only 64 dollars +shipping+extra for a 300W(as opposed to 250). Anandtech did a review of this case as well. http://www.anandtech.com/showdoc.html?i=1150

Their review isn't as great as it should be...but the problems they listed, I never noticed.