http://edge-op.tripod.com/grouch/notes.html

Many of the auto-install programs of Linux distributions create only a "native" and a swap partition. There is nothing inherently wrong with this except
     for the inconvenience noted above. An advantage to having one partition that holds all of your system is that you won't run out of room in, for example,
     /var when /home or /usr have lots of space remaining. 

     Here are some usable, roomy sizes that allow for growth and beginning experimentation (unless you're doing some serious serving, in which case you
     need a lot more information than you will get here!): 


The size shown in [ ] is a *reasonable* maximum, not a system limitation.

               Size
Mountpoint   [Up to]     Description

  /boot        5 MB   May not be able to set it this small, 
            [ 15 MB]  depending on geometry.
                      May not be needed, with newer versions of LILO.
                     
  /          128 MB   The / directory holds everything, but the partition
            [ 1 G ]   that holds / does *not* have to contain everything.
  
  /var       256 MB   This could be larger, depending on services and logs.
            [ 1 G ]   Debian stores downloaded packages in a subdirectory of
                      this, so make this larger if possible.
  
  /usr       512 MB   Depends on how much software you install!
            [ 4 G ]   Bump this to about 2G if you have the space.
                     
  /home      512 MB   Make this one large if you download a lot or have
            [ how     multiple users on the machine. This one should hold
              much    all of 'your' stuff. By putting it on a separate
              can     partition, you can later change distributions without
              you     disturbing your personal files. Just don't format it
              give    during the next install or upgrade.
              it?  ]  Many distributions default to placing the root for the
                      ftp and http servers in this directory. This is another
                      good reason to expand the partition holding /home.
                     
                     
  swap       128 MB   Use the guidelines given with your distribution.
            [ Generally, swap should be double the amount of RAM installed.
              But systems now seem to have more RAM than is needed for all
              running programs. Most people with 64 MB of RAM or more have 
              little need for more than 128 MB of swap.
              Your mileage may vary. ]