Need a portable laptop for work

Budget: Up to $1k pre-tax

Size: Thin and Light (13" - 14" screen)

Brands: No HP. I'm heavily leaning towards a Thinkpad, but I'm looking for alternatives because they're definitely pricey

Usage: Software development. I mostly like working with Linux, and sometimes I need to get a VirtualBox up and running.

Mobility: The laptop will be mostly used at home, but I need something that I can take on the road without notice.

Games: None, not even solitaire.

Battery life: Consistently above 4 hours would be great. Between 3-4 is pushing it

Buying online/in person: No personal preference.

OS: I use Linux for work at home, OS X at the office and Windows for my home PCs. I really don't care.

Screen Specifics

Screen: Widescreen, I think? Matte/non-glossy
Resolution: UXGA - 1600x1200/WSXGA+ - 1680x1050/WUXGA - 1920x1200; either of these would be wonderful

Build Quality and Design
Are the notebook's looks and stylishness important to you?: Not particularly, but nothing awkward (like a battery cell that clearly sticks out from the bottom, etc.)

When are you buying this laptop and how long do you want this laptop to last? I'd like to buy it this week, and I'd like for it to last for about 2 years. Anything more than that is a bonus

Notebook Components

HDD: 128GB is the minimum. 256-320GB would be great since I could multi-boot

Optical drive: I prefer none, but a DVD-player if it has to have one

Things that I think are obvious: Ethernet/HDMI port (both of which the X1C lacks), USB3.0, Webcam, minimum 4G RAM, pref. upgradeable

I've been looking at Thinkpads a LOT lately, particularly the T430/T430s/X1C. I've also thought about a Macbook Air, and I hear Toshiba has some good machines... but I've been out of the buying market for a while and have no idea what my options are at the moment. Any insights are greatly appreciated. Thanks!