While this is certainly possible dual booting Linux and windows is not for
the faint at heart. I seriously suggest that you backup your important data
before you attempt this. I'd use a program like Acronis TrueImage or BootIt
NG to make a full setup of the system for easy restoration in case something
screws up during the attempt.
You might want to try a version of Linux that is easy to use. Personally I
use Xandros
http://en.wikipedia.org/wiki/Xandros . There is a free version
called Xandros OCE. Xandros installs quickly, gives you a dual boot option
during setup, and networks easily with Windows. It comes with a version of
Crossover (based on Wine) which allows you to quickly and easily install a
variety of Windows based applications like WinRar, WinAmp, Microsoft Office,
etc