Maximum memory for Dimension 2400

Hi there,

I'm trying to upgrade memory for a friend, so I had a look at the online manual which says the following:

Architecture:                DDR SDRAM
Memory connectors:  two
Memory capacities:   128-, 256-, or 512-MB
Minimum memory:    128 MB shared DDR SDRAM
Maximum memory:    2GB
Memory type:               PC2100 (266-MHz) or PC2700 (333-MHz) DDR.  SDRAM (non-ECC)

The bit that confuses me is that the machine has 2 connectors.  Memory capacities go up to 512mb but maximum memory is 2GB.  How can the macine take 2GB if there's only 2 connectors and the highest capacity goes to 512mb? 2 x 512mb = 1GB.  Some memory websites are offering 1GB sticks but if 1GB is the limit, then am I not better off installing in pairs i.e. 2 x 512mb?

Thanks in advance.

Emlyn.