When I was first starting with Linux, I was in the same position.
I absolutely did not want to risk my Windows XP install because I no longer had the original disks for some of the installed applications.
Also, I was doing most of my trying of distributions on an old slow test machine and found many of the installers to be ambiguous at best.
Most of them were not a problem. But I had one of the more popular distributions scramble my multiboot setup at a time when I did not have the knowledge to repair it.
Knowing that that was always a possibility, and after finding out the PCLOS was the only distribution whose live CD worked on my machine allowed me to use my dual monitor set up and actually change the scan rate such that I got no headache, I went with a PCLOS dual boot install on my main machine.
I still was not brave/trusting enough to use the normal installer and allow it to repartition for a dual boot system.
So, since it was a desktop machine with room for an other drive, I set it up with a second hard drive just for Linux and set GRUB up to chainload the original Windows install.
And just to be extra safe, I installed Linux with the power cable unplugged on the original drive containing windows. That way, I was able to install Linux on its own drive and test it thoroughly before even powering up the Windows drive again.
On top of that, since I really really did not want to lose my Windows install, I imaged my windows drive before I did anything.
It worked out just fine. And, since I still don't want to take a chance on losing that Windows install, I always unplug that drive when I do a major update or version change on the Linux install. This is mostly because I do not trust Windows.
So, before you do anything, do a search on the forum for Windows and chainloader and pay particular attention to posts by Old-Polack.
Now, the truth of the matter is I and others have done many dual boot installs on Windows machines using the defaults in the PCLOS installer with absolutely no problems. You will probably have no problem doing it that way.
But, since I know that Murphy as in "Murphy's Law" is just waiting for me to have a moment of brain fade during an install, I never "risk" my main install of Windows using the default installer.
Just take your time and use the live CD for a while and read the forums before you take the leap.
Still, the second drive and chainload method is by far the least risky approach.