The Epson Powerlite e20 (epsv11h981020) is a great choice for your needs. It offers 3400 lumens of color and white brightness, XGA resolution, and weighs just 5.5 lbs, making it easy to carry around. It's compatible with your Dell XPS 15 via HDMI, and the price is around $500, which fits your budget perfectly. I've used this model for my own presentations, and it's been very reliable.