For me, the essence of partitioning a drive is like having a filing
cabinet.. each partition is allocated a particular use.. on an 80gb drive, I
split it into four equal parts.. partitions are for OS and applications,
games, installation files for stuff picked up from the internet for which no
original installation media is available (eg, drivers, free programs etc)
and lastly a data partition which I use for quick access.. this works well
for me.. it is not the easiest way to set up and work a system because there
is always an element of discipline and some knowledge in how to run and
organise it..
Regarding the data partition, it exists purely for quick access.. note that
one should ALWAYS have backup (saved) in a medium which can be removed from
the computer and stored safely.. as far as backing up is concerned, it is
easier to back up the contents of an entire exclusive data partition than it
is to sort through one giant partition..
For this reason alone, I would suggest that at least two partitions are
created.. allow at least 20gb for the operating system and applications,
more if you are in the habit of collecting applications.. on a large drive,
eg 160gb, allow at least 40gb for OS and programs..