If you're trying to run many applications at once, you need not only a lot of
RAM, but a large swapfile.

For reasons too complex to go into here, you need a swapfile at least twice as
large as the system RAM. If not, you can run into situations where the machine
slows down -- even though there's enough RAM for the loaded programs.

If you don't have a large-enough swapfile, you need either to enlarge it, or get
a larger hard drive, or add another drive. Most versions of Windows let the user
override the OS and select the size and location of the swapfile.


Adding RAM is often a cheaper solution, but its not
always a better one.

When is it not, and how often? (not counting systems in
which 'Committed Bytes' never approaches total RAM)