In order for you to accomplish this let me point out to you that you need to violate Apple's EULA or "end-user license agreements" as to call it that way, and it's against the Law. And here in america if you'r breaking the law you know how the story goes… but anyways, Lets assume that you still want to brake Apple's End-user License Agreements, you need a patched Mac OS X Image.

I will not provide the link but you can do some research on Google.
Keep in mind that Mac OS X does not install Hardware like Windows does, remember that Apple designed they're OS to handle specific hardware and they are very few. So before you install Mac OS on your PC make sure your current hardware is supported before you go thought the hassle (there's a list of supported and unsupported hardware around).

So, lets assume hardware support is not an issue and you already got you patched image recorded into you DVD-R or DVD DL, whichever applies to you, you're going to need a Partition Manager to resize your Windows Partition with, my favorite is GParted Live CD i'll provide the link at the end.

So after you've resized your partition to leave at least 20GB of unpartitioned space in your hard drive for OS X you'll need to create a FAT32 partition on that unpartitioned space and restart and boot into your OSX CD and "erase" the Fat32 partition with the Mac OS X Disk Utility and install OS X on that partition….

Install OSX, Restart and boot into the Hard Drive leaving the DVD in the tray and you'll see the OSX Bootloader or you might get a "B00 Error" or something like that. If you do get an error then there's a procedure to correct that and no need to panic. If you dont get the error you should be asked which OS you would like to boot from.

Also keep in mind that doing all this would be easier if you posses at least basic understanding of how computer hardware and software interact and work with each other.

Backup your data before you do any of this and hope that helped.

GParted: http://gparted.sourceforge.net/livecd.php

Summary of File Sharing:

Mac OS X 10.0 and later allow you to share the contents of your Public folder.
Others can also copy files to your Drop Box folder located in your Public folder.
You set up File Sharing using the Sharing and Network panes of the System Preferences application.
You can further define your Sharing privileges using the Info window.
Mac OS X offers services that allow you to both share with and connect to other operating systems, such as Microsoft Windows.