U can do this for ur 16o GB HDD:
C: containing Win XP--------------------------------> 10 GB
D: containing My Documents (only MS office files) ----> 5 GB
E: containing My Music------------------------------> 25 GB
F: containing System Cache files (used by XP)--------> 2 GB
G: containing Games--------------------------------> 50 GB
H: containing Backup--------------------------------> 5 GB
I: containing Softwares (installed on the PC)---------> 20 GB
J: containing (watever u feel like, say movies)-------> 20 GB
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Btw, this is wat i hv done to my 160 GB HDD:
Win XP on C: (its a default)------> 10 GB
Music (D: drive)-----------------> 5 GB
System Cache (S: drive) --------> 4 GB
this, u will hv to make it as soon as u make a fresh install of XP on ur HDD and it shud be twice the size of the RAM tat u hv, so for Eg, a 2 GB system RAM wud mean u shud hv a 4 GB Cache partition (i fu want abt "HOW TO" then i can tell u

)
Software -----> 5 GB
Torrents -----> 15 GB

Backup (or files/ applications to be burned onto a CD/DVD)---> 5 GB
Xtreme-I (this is my game partition) ----> 30GB
Xtreme-II (this is my other game folder) --> 30 GB
Linux -----------------------------------> 15 GB
Movies----------------------------------> 30 GB
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THe rest is unallocated space
Cheers n e-peace...