no one ask any questions... fine

how much time do you have spare in the first 7-14 days?

as I would recommend to install your system from scratch and get rid of windows in the first place (can be reinstalled at a later point but the fact that you have to reinstall overrates your own laziness)

I recommend ubuntu as well but as jd said it is a bad joice for learning your way around GNU/linux. Depending on the time you want to spend: not much - ubuntu,xubuntu; a little - debian with kde; some - debian testing with xfce; some more - debian testing with fvwm; no evenings - archlinux; not even enough sleep - slackware;

If you need help on deciding, the scale of time you need to spend to learning experience is quadratic. For ubuntu and debian you need to know the fact that after knowing them you know the debian-way of GNU and this knowledge will help you through most problems on other distributions as long as they follow some kind of a standard behavior. For Arch and Slack you will need to spend the most time behind your monitor, what does not mean that you don't have a running system within hours but you are forced to learn your way around on a CLI (command-line-interface) within GNU/linux stuctures.

A good start off is to use a pendrivelinux with possibility to persistent working (you don't have with cds without writing to your harddrive). There you are able to startup non-persistent if you are on a killing-spree of tryout and learning by doing, once you know how something works you reboot the pendrivelinux persistent and make the changes you just learned from screwing your non-persistent system several times (that does not count for boot sequences as you cannot view them changes happen on non-persistent mode).

I hope that helped.

For all other things, try to find someone who already knows his/her way around just in case you cannot even boot your system anymore.

PS don't even think about using gentoo, the only thing you will learn in the first 3 days is how many code your pc is able to compile...