hello golden duck im a bit of a noob too
welcome to LQ's, its a nice place to learn about linux.
you can dual boot XP and a linux distro, that is have a screen giving you a choice of which OS you would like to run when you start your computer. its pretty easy to do on the same harddrive, it involves 'partitioning' the harddrive, and both windows and any linux distro will allow you to do that on installation. just remember its better to install windows first, then linux second, otherwise windows will selfishly rewrite the MBR (Master Boot Record) and not include linux.
i suppose your most immediate concern is which linux distro to start with. may i suggest Vector linux, as it has many things working 'straight out of the box', such as music and video support, and its also set up in a way for you test out different 'desktop environments' and 'window managers', and is generally a good distro to get a feel for how a linux system can work well. i started with Fedora Core and it nearly put me off linux for life, then i switched to Vector and everything seemed alot clearer.
to learn about linux in general, just bookmark the forums here at LQ's, i learn alot by just watching other peoples threads and trying the same things out on my own system. a good link is http://www.chongluo.com/books/rute/
the going can be quite tough at first, but take small steps and it will get easier as you bring your system together. its very rewarding