It has window xp professional installed in it. I will provide recovery cds for window vista and window xp both.

---

The last thing you need to worry about if you are out calling on a client is how to connect to the internet. The ThinkPad SL400 comes standard with WLAN built in, and offers a variety of available wireless connectivity options. The WWAN feature gives you embedded Mobile Broadband capability for faster connectivity, upload and download times. You can take advantage of your carrier's entire network, instead of being concerned with connecting to a specific LAN. In selected cities, the ThinkPad SL500's WiMax capability lets you connect over several miles' radius without having an agreement with a wireless carrier.

Our user friendly Rescue and Recovery tool lets you quickly diagnose and recover from an external virus or spyware so you can get back to your business as quickly as possible.

Contemporary, stylish design

Like every ThinkPad, the SL Series is black to give it a serious, businesslike exterior. Its glossy finish gives it an edgier, more personalized look. Its vibrant-view and anti-glare displays deliver an outstanding picture, whether viewing spreadsheets or watching videos.

Reliability you can trust

ThinkPad SL400 protects your investment and your valuable data with several reliability features. Its Active Protection System protects your hard drive when sudden movement is detected. Its spill-resistant keyboard protects the internal components of the ThinkPad SL400 by funneling spilled liquid to a drain hole in the bottom of the system.

Processor(s)
Processor Mfr Intel
Processor Core?????2 Duo T5870
Processor Speed 2GHz
Cache
Cache standard, primary 0KB
Cache standard, secondary 2MB
Magnetic/Optical Drives
Hard Drive 250 GB
Hard Drive interface type SATA (Serial ATA)
RAM
RAM standard 2 GB
Display
Display 14.1 active-matrix/TFT/XGA
Display, maximum resolution 1280 x 800
Miscellaneous
Modem included Yes
Network interface card included Yes
NIC type Gigabit Ethernet
Wireless NIC included Yes
Bluetooth capable Yes
Battery Type Lithium Ion
Form factor notebook
OS Microsoft Windows XP Pro

Fingerprint reader
Camera
Modem
DVD recordable

price : $600(OBO)