Best Way to Install an OS?

I have a debate going on here regarding the best way to install an OS on a standard desktop workstation. I would like to ask for the forum to settle the debate. 😉

My side of the argument:
Install a single partition to the primary HD, and load Windows XP onto the full capacity of the partition, labeling it C:

The other side:
Paritition two segements on the primary HD, loading XP on the 2nd partition, and DOS on the first. The idea being that DOS can be used to recover the second partition if things go bad.

Let ‘er rip…