There are lots of things to also take into account like ... what is the purpose of the box? What is acceptable performance? ... etc.
On my FC2 desktop, I have 500MB of Swap. That should be all I need for the tasks that I do. I have a couple of Linux servers that have 500MB and 800MB of swap respectively although they never actually use more than 5% of that. / for the box that I have people access is 20 gigs and /home is roughtly 190 gigs. All my slackware packages are on /slackware and I am about to get another 200 gig HD and mount that as /share.