Technical Details, including type and maximum supported:http://support.dell.com/support/edocs/SYSTEMS/dim8250/specs.htm#1105389
Just keep in mind this is not the current DDR RAM you can buy from places like Newegg. This is the older RDRAM, but is still available from places like Amazon
. This was just the first site I found carrying it, and you might be able to find it for a better deal, or different configurations elsewhere.