First, "I'll add on to it" just doesn't work. You're buying a laptop. You won't be upgrading it. Most things on the market today will emphasize memory and storage because those are the numbers the masses flock to. For 1k, grab a laptop with an i5 or i7 in it and you'll be set performance-wise for the foreseeable future.
If you want to edit HD Video, grab something with a quality GPU.
Other than those tips, honestly, go with whatever laptop feels best to you. You're going to be using the keyboard a lot. Don't sacrifice comfort for a smidgen of performance.
As for brands, Asus and Toshiba have the lowest rates of hardware failure in the industry (12.2% and 12.4% within three years) Dells and Macs are in the middle (14.6%) while HP is incredibly high (almost 25%).
Asus might make a good notebook in your price range. They also have the advantage of using an Asus motherboard instead of the cheapest one available, which is what the other retailers use. (Asus and Gigabyte make the best mobos in the business now that Abit was bought out).
Toshiba makes a great value computer in the 500-700 range. They might not have the cutting edge technology, but they make a solid product. Few disappointments.
Sony has a nice style to them, but they overcharge compared to other Windows-based laptops.
I can't recommend Gateway, Emachines, Compaq or HP. They make the worst products in the business right now. I have mixed feelings about Acer.
Lenovo makes a quality product. I can't complain there.
If you're looking for style, a well-built laptop, and an incredibly simple (also restrictive) OS, then, while I could never use a Mac, they may be right for you.
Hope this helps. Obviously you want to be running a 64-bit version of Windows 7, and if you have 4GB of memory, that's more than you'll need. Don't worry about HDD space. That's why you store your media on an external source.
