Costco has recently changed their return policy (90 days), so I'd be careful going that route, but they do extend the manufacturer warranty to 2 years...
Here's a 16 inch Acer notebook (AMD Athlon 64 1.9 Ghz, 4 GB RAM, 160 GB HD, DVD Burner, draft-N wireless) for $599. I have an older Acer notebook that I've had for 5 years, still running strong (needs to be blown away and reformatted, weekend project).
I was going to recommend TechBargains, but Matty already did. Newegg always has decent deals. But if you can take advantage of Dell's Employee Purchase Program, you might as well see what you can do there.