Any computer experts out there? (Do you build them, fix them, know the quality of them?)

OK I need to settle something with my grandfather. he is buying me a new laptop for Christmas. Within a $700 range. I HATE windows vista, and want to take it off and replace it with Linux. Does this in any way effect the computer, or its warranty? He also thinks vista’s problems are fixed. He also thinks that its dangerous for me to be putting other operating systems on this computer. Please give me all facts you currently know about vista. Including warranties, its capabilities, and “HORRIBLE” dangers of taking it off of my computer. Please provide links if possible. I am looking for people who really know their stuff. Thank you so much!!