Most likely PCs. . .in my school and other schools I've been to use HP computers. . .but in the university I will be attending use IBM/Lenovo PCs & Apple PCs. . .
What I'm trying to say is. . .it depends on the high school. . .but. . .my guess is PC
1. Which OS will offer a more "all-around" user experience out of the box? Mac or Windows?
Mac is you mean stability. . .or Windows XP. . .not Vista. . .
2. Which OS will have better software and be more user-friendly?
Windows. . .
3. Which OS will be more safe and secure from viruses and pop-ups?
Mac since it is less popular. . .however. . .Windows is also safe if you install Internet Security software. . .
4. Can I get either a MacBook or Dell laptop for under $1500?
Yes you can. . .you can get a 2GHz Macbook for $1149 (CDN). . . and as for Dell. . .it depends what kind of laptop you want, but I am certain you can get Dell XPS M1330 for less than $1500. . .as well as Inspiron, Studio, Vostro, Latitute laptops. . .so I guess it depends on what the configuration is. . .