Just tell them you didn't have to buy Nero, or WinDVD or even MS Office. A $50 retail copy of Mandrake comes with all that functionality (K3b, Xine, OpenOffice) and more. Compare that to a $200 copy of XP, add the cost of the extra software they'll need (Office XP alone adds $300+), and then ask them whether using Windows is worth 10X the price. "Do less for more" really should be M$ new slogan.

click on the link in my sig about advocating linux , follow some of them comments

Heh, my best example of why Linux is superior, is my computer.
It's quite literally a piece of excretia, but it runs Linux, just like my gaming computer runs WinXP Pro, I don't think my computer could even run WinXP... - If that makes sense?
Show them the command line.. Basically, I've only been using Linux for about 1 year now.. Before that I used Windows.. So I never really understood the power of a command prompt.. Then recently I started getting into the command line, I can do the majority of tasks that I want, just using the command line..
Now, a LAN, I assume your friends are gamers :P
Linux mightn't be the best operating system for a gamer...

However, for everything else, I find Linux does the job, sufficiently if not better.

Most people I know run Windows too. But then I'm in IT and support windows servers and most people I know are in the same situation, those broken windows boxes keep us all in jobs. I could people I know did start to look at linux seriously after I made the switch. You have to work hard to be at the top of your field to be taken seriuosly, if you can get to that point, become the person who knows everything, the "go to man" then some people will start to think "hey, this guy is smart maybe I should look at this linux thing too". A programmer I work with was going to buy the Microsoft anti-linux cd and have it shipped to me as a joke and he admitted that M$ web site crashed everytime he tried to order the CD

whats on the MS anti-linux cd?

I never did get it
Its supposed to be a bunch of white papers and migration tools to help you migrate from Linux to Windos and a bunch of marketing material telling why M$ is better.