Memory limits for Windows XP , Windows Vista

Ever wondered how much memory (RAM) you can put in your machine?
 Besides the physical number of slots for RAM, here are the Windows limitations.  As you will see the Windows answer for more memory is ’64 bit’. 

Vista + Wireless = Sometimes

Sometimes you try to connect to a wifi in Vista and you get:
 
Access ‘Local Only’
Instead of
Access ‘Local and Internet’
In the Network and Sharing Center
 
And you can’t browse the internet (but you can access local devices).