I upgraded my RAM from 1 to 2 GB (2x1GB PC26400 200pin DDR2) but my laptop seems to only see this as 1GB. How do I get it to see both?
Check to make sure both modules are firmly seated.
If they are, see which one isn't detected (Dell diags; F12 at powerup). Then swap the modules - if the fault follows the module, one DIMM is bad. If it doesn't, one socket is bad.