Need Info on Partitioning...

Ok, im no hardware noob or anything, i just need some info maybe a link to a good article on partitioning your hard drive. I dont want to know HOW to do it, i can do that, i just need the effects of it explained to me... For example i dont understand why people partition... dont you get better performance if you use the drive like normal? And doesnt windows and the rest of your programs/games run better if they are all on the same drive? I read somewhere that partitioning affects your drives fragmentation negativley too... I see some people have like a 60gb drive and make a 10gb partition for windows, 20gb for mp3s/movies, a game partition, etc. etc. I would like to know what the benefits are of doing this... and i always thought the only people who would do it are ones with big hard drives like more then 40gb.. because the bigger the hard drive the slower it performs right? As you can see im a little confused... any helpful links and personal experience is wanted.

By using seperate partitions you can load all your good files on the D: drive or secondary partitions and leave the C: partition for winblows and the other program file applications. Then when you accidently hose your OS you can safely reinstall it and not worry about all the other files you have since they are safely onthe other partitions. Though some may require a reinstall, you still wont loose that info when you reformat C: which you would with a single partiton, however with a single partition you risk loosign EVERYTHING. so its safer to keep things seperate.

It helps in organizing things.. C: system files
D: games
e: graphics applications
F: MP3/music
and so on

Formatting bigger drives takes alot longer

Its not negative for fragmentation so far as I am aware.. fragementation is the same no matter what. But it does let you fragment 1 partition at a time so you can adjust your defrag times for more conveniant blocks rather then starting it and waiting 4 hours for a really big drive to defrag the whole thing

The other reason for partitioning is if you have two or more operating systems on your computer. For example, my computer is running both Linux and Win98SE, so my partition scheme looks like this:
Disk 1:
Partition 1: 1.5GB Windows OS
Partition 2: 0.5GB Linux OS
Partition 3: 2 GB Linux virtual memory partition
Partition 4: 56 GB Windows programs/data partition
Disk 2:
Partition 1: 60 GB Linux program/data partition

This site goes over partitioning pretty well:

http://www.pcguide.com/ref/hdd/file/part.htm

lets not overlook less HDD wear with partitions and faster access times.