Memory usage less than 80 percent?

[darkstar845]

Is there a rule on memory usage so that the computer is always responsive? Like if you have 4GB of ram, you should not let memory usage go beyond 3.5GB?
I know about virtual memory but is there some sort of rule about ram?

 

[rgd1101]

Windows will handle that.

 

[profkefah]

what windows bit you had install
64 or 32 bit
if its 32 then u have to install 64 bit windows
if its 64 then you have problem