Compaq Presario Notebook V3000T\r\nI replaced the

Thanks to Microsoft Knowledge Base for help with my answer:

First, find out what the maximum amount of memory is. This is generally listed by most of the manufacturers. This will let you know what upgrade potential the system has. Next, determine how the memory configuration is when you buy the system. For example, a laptop that has 2GB of memory can be configured as either a single 2GB module or two 1GB modules. The single memory module allows for better upgrade potential because by adding another module you are gaining more memory without sacrificing any current memory. Upgrading the two module situation with a 2GB upgrade would result in the loss of one 1GB module and a memory total of 3GB.