In the market for a new notebook (by which I mean one that's actually new, not a refurb)? Best Buy has a pretty nicely equipped Acer Aspire for just $399.99 (plus sales tax in most states). Shipping will run you about $20, unless you live near a Best Buy store and can just pick it up.
The Aspire features a 2GHz dual-core Pentium processor, 2GB of RAM, a 160GB hard drive, and a 15.6-inch wide-screen LCD. It also has a multiformat DVD burner, but I think its most impressive asset is 802.11n Wi-Fi (which also supports b and g, natch). That's a rarity in a budget-level notebook.
The Aspire weighs about six pounds and measures 1.5 inches thick, so it's reasonably travel-friendly. As for horsepower, I think it has more than enough for everyday computing--and way more than your basic Netbook, which costs about the same (if not more). I haven't used this particular model, but I've reviewed several Acers in the past year, and they were all very solid. Like most, this one has a one-year warranty. Great buy, IMHO.