Noob question: want to go back to basics

[chee]

i have a Dell Inspiron 6400 that i have been running Ubuntu on for about 4 years and really liked it. i have a 120gig hard drive where 10 of that is for a small windows partition for just in case times. originally i had a friend set things up for me but my computer has been running really slow lately and i have no idea why, so i would like to go back to the basics of Ubuntu and learn to set things up (like programs i want and other things) but have no idea where to start. there are a lot of programs on my computer i don't use and would like to start from scratch as i mostly surf the net and burn some movies at times.

any help as far as tutorials or if it is real easy just telling me how to do it or whatever would be great, i am up for reading and learning for sure but really want to learn stuff i will use. thank you

[Pumalite]

http://www.linux-tutorial.info/index.php
http://www.linux.org/lessons/beginner/toc.html
http://howtoforge.com/taxonomy_menu/1/1/50
http://www.littleigloo.org/tutorial.php3
http://www.geekgirls.com/
http://www.ubuntugeek.com/
http://www.ubuntugeek.com/tag/ubuntu-hacks/

[chee]

i'm startin with the first one and we'll see where i get.

thank you

any other suggestions are always welcome