Special Partition for Windows

I've heard of people who have partitioned their harddrive then installed windows on one partition and keep their data on the other partition.  Anyone have a link to how to do this?

Also, what are the advantages and problems that arise from doing this?

if it's a new hard drive, just dig up instructions for fdisk.exe from somewhere.  if it's an already formatted hard drive that you want to re-partition, you'll need something fancier.  i've had good results with Partition Magic myself, but that costs money.  parted is free, but doesn't run under windows afaik.  you should be able to dig up a liveCD which will work though.

advantages to partitioning:
1) keeping data seperate from your Windows installation makes it easier to format and reinstall/upgrade your OS without risking any of your data.

2) if your data is frequently modified, deleted, added to, etc, keeping it seperate from your Windows installation reduces the effect of disk fragmentation.  more of a concern for older Windows (ME, 98) which only use FAT filesystems.

3) if something corrupts your filesystem, keeping drives partitioned makes it less likely to affect the whole hard drive, and only losing one partition instead.

the only problem thats likely to arise is inefficient use of disk space if your partitions aren't sized well (ie: if your data partition is full, but you still have 10GB free on your Windows partition).  however, if you have a program like Partition Magic or parted, you can resize them at will, so it's not an issue.