How much RAM does windows home premium 32 bit support?

Hi, I have a toshiba satellite pro c660 with 2gb of ram installed. I want to upgrade this to 4gb. I still need to check that my CPU and motherboard will support the ram but for now I just want to know if my operating system will. I am pretty sure that I can olny install up to 4gb but I just need to make sure.

Thanks for any help, david.

Depends on the version OS you're running and your hardware:
Windows has 4GB limits for 32 bits systems (xp/vista/7), but the 64 bits versions go up to 192 GB.

Generally this is what 64 bits OS was made for, 32 bits always had and always will have these RAM limitations.

So, too awnser the question, it's almost certainly ok to upgrade from 2GB to 4GB without issues. This site has all the windows versions and their (theoretical) GB limits:
http://www.crucial.com/kb/answer.aspx?qid=3743

For your motherboard, check out the manufacturers website and it should clearly mention it's max GB RAM somewhere.