I have a used Dell XPS M1530 Laptop for $500 OBO.
It runs great and is in good condition, except for a dent in the hinge, which I have posted above. Seems to be just a cosmetic issue, as it has never given me any problems.
It has been taken care of, but since it's been used, the battery life now lasts for just over an hour, give or take (depending on usage).
It still has a few days left on its warranty, but literally only a week, so that's not really a selling point here. You can extend it with Dell if you want, though.

Specifications:

<ul> <li> Operating System: Currently runs Ubuntu 11.04, but I can install Windows 7 Professional instead when I wipe the computer for you, if you want. <li> Processor: Intel Core 2 Duo T9300 @ 2.5GHz <li> Memory: 4GB RAM <li> Storage: 250GB 5400RPM Hard Drive <li> Display: 15.4-inch WXGA (1280 x 800) CCFL glossy screen <li> Graphics: NVIDIA GeForce 8600M GT, 512MB <li> Network: Intel® Wireless WiFi Link 4965AGN (802.11a/b/g) with external wireless switch and integrated ethernet <li> Camera: Built-in 2 Megapixel webcam <li> External Media: Slot-loading DVD±RW drive, Built-in memory card reader (SD/MMC, MS/Pro) <li> Inputs: 3 USB ports, VGA, ethernet, HDMI, IEEE1394 (FireWire), S-video <li> Extras: fingerprint scanner and multimedia remote (I'm not sure if either of these work in Ubuntu; I never use them so I haven't tried it out) </ul>

Can also meet you in SF Financial District if more convenient for you. Please let me know if you're interested.