before installing linux on your p.c why not download a live linux os ,these live cd,s can be run on your p.c just like a program and they dont affect your current os
live linux cd,s come in all sizes,there are small linux distro,s like "damn small linux"(http://www.damnsmalllinux.org/download.html)and larger distro,s like ubuntu(http://www.ubuntu.com/)
all you need to do with these is make sure your dvd-rw is set as the first boot device in bios(press delete at start up and go into advanced bios settings,remember to save and exit set up before leaving bios),then your live cd will boot up and load,all usernames and passowrds will be shown onscreen,but most linux live cd,s use "root" as username and "toor" as password
i personally like slax popcorn(http://www.slax.org/) ,its a 115mb download and its quite easy to use,but for a full list of live cds avalible for linux go to http://www.livecdlist.com/?pick=All&showonly=Desktop&sort=&sm=1
another good idea is to create a partition on your hard drive,or add a second hard drive and install linux alongside windows xp,this way you have the best of both worlds
good luck mate