good day,

well, i am guessing that you are running windows nt / windows xp?

and, i am guessing that you probably will have anywhere from 30gb to 70gb for data storage?

i have always done what you are outlining -- i.e., a separate partition for my os and programs, and then multiple partitions for various data items.
having said that, i have never experienced any sort of crash, major corrupted area, or data loss [since 1986 up to today], so at one level i cannot honestly say why i have done so [having said that, i will say that i will continue to do the exact same thing to the next computer/hard drive i purchase].

you might want to do a google search on "partition size" and see how the size of your partition affects your cluster size which affects the lost area known as "slack".

and, i will admit:
a) i have always run gibson corporation's spinrite on my hard drives -- it will mark/repair any/all areas that are unusable [this is a gift from the gods at the same level as fire]; and
b) i have always used partitionmagic to partition my hard drives

you can read about spinrite at www.grc.com -- this site may be kind of geeky, but i consider spinrite as totally necessary to examine, and to repair, your hard disk.

and, i think partitionmagic is also a gift from the gods [not quite at the level of fire]. you can partition and/or resize your drive on-the-fly all without losing any data.

hope this helps.