How do I keep my laptop in good condition?

[larabond3]

I was recently given a brand new dell laptop, because I am moving out and going to a University, so I needed my own computer.The computer I have at home is slow and filled with spy-ware, mostly due to my little sister and all the crap she downloads. I want to take really good care of my new laptop, so does anyone have any advice?* What should I avoid (such as, kinds of sites)?* What programs free or inexpensive should I use to protect the laptop?* How can I maintain its speed?* Any tips would be greatly appreciated,