I have been using Linux dual boot machine for a few years now, and especially like the SuSE Linux distribution which is very easy to install even if you have never used linux before. The graphical/text installer can actually resize a Windows NTFS partition and let you use a part of an existings HD, in fact this is what I have on the computer I am sending this posting from.
A few pointers if you are willing to give it a shot:
1. Always back up!!!
I remember reading once on a CD box "Don't be a fool back up is cool!" the guy/girl that put that their was very smart and I became so ...
.
The installation will probably go flawlessly as I have done it numerous times without major problems, but I know nothing about the pc/laptop you plan on using so back up.
2. If you are going to install on the same HD run the Windows disk checking utility and the defrag utility, before the install, to have windows rearrange everything more efficiently before Linux starts slicing its part.
3. If you wish to keep and use both OSes at different times, which in many cases is required (not all programs are available on all OSes). Create an FAT partition so that you can have a place where to store information and use it in any operating systems. NTFS will not be writable in Linux and Windows, of course, cannot even see a standard Linux partition Reiser or ext2/3 etc.
If you wish to try SuSE check out
www.opensuse.org if you wish to try something else checkout
www.distrowatch.com, you will find CD distros there Knoppix is a really good one e-Live is good looking one
. There is a lot of variety in Linux and it all comes down to what you want, but it is a great OS!
I hope this helps, good luck.
George