THIS might interest you.
tested/validated = your warranty coverage
If you go beyond 4GB and brick the motherboard, it will not be covered by the Dell warranty.
Just be aware there is like five versions of the 530 and only two of them are known to support 8 GB of memory. Also the 530 is an Intel based motherboard while the 531 is an AMD motherboard. Totally built by two different companies. 530 by Foxconn and 531 by ASUS.
This is useful to know. The BIOS remapped the PCI address space above the 4GB address line when I installed Windows 7 x64. As for "bricking" the system with a memory installation - that can happen anytime you open the case.