Most desktop replacements (so named for having giant screens, full-size keyboards, and other desktop amenities) start at around $800-900, but Buy.com has the Acer Aspire 7720-6155 on sale for just $599.99 shipped. It's a factory-refurbished model, but it's also very nicely loaded.
Indeed, the Aspire 7720 features a 1.5GHz Intel Core 2 Duo processor, 2GB of RAM, a 160GB hard drive, and a 17-inch widescreen LCD. It also includes a dual-layer DVD burner, a Webcam, a 5-in-1 media card reader, and, well, just about everything else you'd find in a full-bore desktop. The only real letdown: an integrated graphics processor (Intel's GMA X3100). Thus, this is not the machine for gaming.
It's also not the machine for travel: Although it weighs a manageable 7.4 pounds, the sucker's downright huge. I haven't reviewed the 7720 myself, but I did cover (and like) a kissing cousin, the 7520.
The paltry 90-day warranty is reason for pause, but otherwise you'll be hard-pressed to find a better-equipped desktop replacement for the price. If you have any hands-on experience with the Aspire 7720, hit the Comments and speak your mind.