Difference between XPS 400 and E510 chassis

[expatriot]

Right now, Dell.com is having a 20% discount on all Dimension 510's.


This makes a Dell E510 with a Pentium D 2.80 Ghz processor/3Ghz memory/160 GB hard drive considerably cheaper than a XPS 400 outfitted with the a Pentium D 2.80 Ghz processor/2Ghz memory and 160 GB hard drive.

That extra gig of memory for less money is very attractive to me, but I am worried that I may have some heat and to a lesser degree noise problems if the E310 chassis can not deal with as much heat would be created by such a machine going full bore (I do know how much 3 Ghz of RAM is and would use it many multiple applications running at once). I know that the E510 chassis is well-designed to dispense heat and contain noise but the XPS 400 boasts superior technology.

What would anyone suggest?