I am reinstalling linux onto a new 40GB drive. I had Mandrake automatically partition the original drive and it made a root, swap and home partition. I think I want to use more partitions for this new drive. How many partitions should I make and what size should they be?

well it depends HOW you intend to use them really... with 40gb to spare, you'll basically want to decide where you're gonna put BIG things like avi's and mp3's if you do them... otherwise it's upto you... i have

/ 5gb
/home - 5gb
/usr - 10gb

on my 20gb drive, and a networked drive of 40gb for mp3. i have lots of /usr as i download files primarily to /usr/src including cd images etc.. so the space get's used up there. you might want a 20gb var directory maybe to put big stuff, as that's a standard place for it. or alternatively use it up in /home if you'd rather put things there. but with 5gb /usr and 2gb / you shouldn't really run out of space system wise, so it's upto you where the rest goes...

Workstations and servers generally have different partitions layouts. There's also no right and wrong. Like acid_kewpie said, it depends if you're going to store large amounts of files like mp3's, avi's, vmware virtual machines, uhm whatever else comes to mind.

For reference here's how I have partitioned the linuxfromscratch.org server:

/ 100 MB
/home 4 GB
/var 1 GB
/tmp 100 MB
/usr 2 GB
/backup 2 GB

My workstations looks like this:

/ 100 MB
/usr 4 GB
/home 1 GB
/usr/src 2 GB
/usr/misc 10 GB

(/usr/misc is where I keep stuff like mp3, vmware, build cd images, and other stuff).