Upto what limit can i extend memory on my Toshiba 1800 s203 laptop

I have a Toshiba 1800 s203 laptop on which i had installed Windows Vista as my operating system. I have a 128 MB in build memory in my Toshiba 1800 s203 laptop. I would like to know that upto what limit can i extend memory on my Toshiba 1800 s203 laptop? Does any body have any idea about it? Kindly provide me the correct information on the above issue. Any kind of information on the above issue would be appreciated.

The Toshiba Satellite 1800-S203 Laptop takes the PC100 SDRAM SODIMMs Memory Type, and comes installed with 128 MB (removable) of Memory. The Toshiba Satellite 1800-S203 batteries and chargers come with one year warranty and 100% compatibility guarantee.

While your upgrading the memory, you should also get a larger, faster hard drive. Toshiba Satellite 1800-S203 Laptop to up to a maximum of 512 MB Memory, the system has 2 sockets to install Memory, already with 128 MB (removable) standard Memory installed.

Toshiba stands at the forefront of high technology and plays a leading part in the development of advanced electronics and the manufacture of innovative products for consumer and specialist markets. I got a pair of 256MB PC100 SDRAM modules. The Toshiba Satellite 1800-S203 Laptop takes the PC100 SDRAM SODIMMs Memory Type, and comes installed with 128 MB (removable) of Memory.