I currently have - according to my saves folder - one save file only and its default backup. That is, my immortal dynasty challenge. However, that is not true as I, like many others on here, have inactive save files. I keep them on another hard drive as if I see those in the main menu I will get distracted and play them (and then they will lag awfully) and then get upset over it. So if I start a new save file, that's it, that one becomes the one and only file. I know this style of gameplay is weird, but that is really the only way I can discipline myself to actually playing Sims.
I have plenty of worlds including all EA towns and various custom worlds that suit my tastes. I never got around to installing create-a-world so I don't have any worlds of my own. Some worlds I like to play in frequently while others I only ever used once or twice (such as Lunar Lakes or Barnacle Bay).
As for my inactive save files, there is nine of them. I've not played some of these for a really long time but I intend to get back to them once my new computer arrives. Surprisingly, I could care less about a couple of these... however the save files I really did care about are no longer available. Some have inevitably vanished in different incidents whilst others I deleted accidentally myself. Not much I can do about that, eh?
-M.