I had on 98SE a separate partition (4 x RAM) for my swapfile.
I actually don't bother to move my Paging file (XP's version of Swapfile) to a separate partition as you can 'tweak' it and limit/set it to any given size using Admin tools.
The Following is a personal opinion. I use my XP at home mainly as a home ent system (Gaming, DVD, Music, TV etc.) I don't compose many letters or do my accounts on it. With that in mind I prefer all my applications to be on the C drive. I have a D: drive for back-up of Saves files, Email, Favourites etc.
On my 80GB disk 70GB is C: and 10 is D:Backup.
I am shortly to purchase another drive to store rip the rest of my CD collection as 15GB of my C: drive are MP3 and wma files which would be better off on another partition in case I need to re-install windows for any reason.
In short, my philosophy is Programs and Applications on C: Back-up and Data on D: and E:
One final point. I have my DVD as Y: and my CDR-R/W as Z: so I don't have to worry when and if I add more drives/partitions.