1. Adding together the amount of memory installed in each DIMM slot.
2. Subtracting that amount from the maximum memory size for your system.
   

Notes:

• For systems with two DIMM slots, Lenovo typically ships its systems with memory modules installed in Slot 1.
• In order to install additional memory, it may be necessary to remove the memory modules from one or both of the DIMM slots.
• Microsoft Windows Vista supports up to 4GB maximum memory (32-bit versions of Windows Vista cannot support 4GB). Microsoft Windows XP supports up to 3GB maximum memory.

• Memory comes in the following standard sizes: 64MB, 128MB, 256MB, 512MB, 1024MB (1GB) or 2048MB (2GB).