As Lynch says everybody has a fave distro mine is Ubuntu u can get info & d/l's here
http://www.ubuntu.com/
As to dual booting if u have WXP now do this in this order
1) select a distro download 1st the live disc if they have 1 on Ubuntu the live cd has an install option
2)burn it to a disk, it must be an iso!
3)try it out on the live 1st if u don't like it leave that distro if u like it goto 4
4)download the install disc if u hadn't already
5)Defrag Windows! that's important!
6)start>restart
7)place the install disk into ur PC before WXP boots
8)follow the prompts write down your username & password then the distro,
Ubuntu in my case, will show it self & be ready to use.
After that you'll see the grub screen where you'll have a choice of which OS u want Linux distro or WXP if u let run it'll always take the linux 1st just use the arrow keys to select WXP. Hope this is what u were after.