what version of Linux is best and why?

If this is your first time using linux, your first choice should certainly be ubuntu. It is the most popular and easiest to use linux distro.

Take a look at Linux Mint 5 (Main Edition) its easy to install easy to use and has much of the software you are likely to need preinstalled.

Linux Mint 5 Release notes

http://www.linuxmint.com/rel_elyssa.php

Linux Mint 5 Download

http://www.linuxmint.com/edition.php?id=25

Linux Mint 5 installation tutorial

http://www.howtoforge.com/the-perfect-desktop-linu...

You download the ISO. image of Linux Mint 5 then you need to create a Bootable CD from the ISO. This can easily be done using Nero Burning ROM or similar software. Linux Mint 5 can also be run straight from the LiveCD you have created without touching your Hard Drive.

LUg.

Mandriva and Mint are excellent alternatives to Ubuntu

Why is too big a question to answer here. It takes years and people still ahve different opinions because it is different depending on your needs and preferences.

Unless you need a really light operating system then I wouldn't stray from the 3 already mentioned: Mandriva, Ubuntu and Mint

If you mean kernel version, 2.6 is best since it's newest.

If you mean distribution, I personally consider Arch Linux the best. See http://wiki.archlinux.org/index.php/The_Arch_Way for reasoning.

for me the best distribution is Ubuntu. I've been using it now for a while and it's just great and very easy to use if you know something about programming. i tried almost all other distributions but none is so great as ubuntu. Kubuntu is also great if you're a KDE fan, but i'm a gnome guy :)