I've no experience with Sager or Falcon, though I know Falcon has a good rep. I've purchased my last 3 laptops from Dell, all Inspirons: 8600 XP Pro 32-bit (5 years ago), 9300 XP Pro 32-bit & Vista Ult. 32-bit (3 years ago), and 1720 Vista Ult. 32-bit (January this year), and all three have never had a problem with any of their components other than batteries eventually dying, something that's going to happen. My wife is still using her 8600, my son's on my old 9300, and the 1720 is my current machine. I use my laptops for everythingâ€”work, home, remote access, DVD burning, gaming, just about anything you can think of that a laptop can doâ€”so all have been put through serious paces without a problem.
Based on your listed specs, I assume you're looking at one of Dell's XPS laptops? If so, I can't speak to the quality of those, but I've been working IT for several years now, and have worked on a lot of Dell desktops and laptops. And while their desktops are not the best, I've had really good experience with their laptops.
Anyhow, my two cents. I'm not a Dell evangelist, but I go to them first because of price/performance and previous experience. If I could afford the Alliance WoW XPS 1730, I'd drop the cash on it in a heartbeat. I build my own desktops.
It sounds like whatever you go with, you should be very happy. Good luck.