Lenovo is releasing what the PC maker is billing as the best of both worlds – a combination of its thin and light laptop, the Lenovo Thinkpad x300,  and its powerful Thinkpad T series of laptops.

“The T400 is our most popular notebook that we sell and make,” says David Critchley, worldwide segment marketing manager for the ThinkPad T Series. “We sell 1.25 million of those a year to large enterprises. It’s durable, rugged and high performance.”

Lenovo’s new entry, the Lenovo Thinkpad T400s, represents a marriage of the X300 and the T400, weighing 3.9 lbs and at just 0.83 inches thick, but with a 14-inch screen and a full performance processor. Lenovo says pricing for the system starts at $1,599, and the laptop will be sold through channel partners and Lenovo's Website.

Lenovo’s Thinkpad T400s also comes with features to make VOIP (voice over IP) easier than ever. It offers hotkey access to VOIP applications including teleconferencing and video conferencing applications. The device includes a 2 megapixel camera. It ships with Microsoft Windows Vista OS and comes with a Microsoft Windows XP downgrade. A choice of two processors is available, the Intel SP9400 or the Intel SP9600. Both are dual core but offer a lower thermal output than some of Intel’s other dual core processors.

The T400s features three USB ports, plus an audio jack on the side that integrates both the headphone and microphone, taking the same headset as the user’s BlackBerry.

For users who want to switch out memory or wireless cards, Lenovo has provided a single screw trap door on the bottom of the laptop for access.

Specifications are as follows:

• Choices of Intel 2.53 GHz Core 2 Duo processors (standard voltage) and graphics
• Choices of solid state drive storage up to 128 GB or 250 GB hard drive storage
• 9.5 mm DVD burner or Blu-Ray player
• Ethernet, Wi-Fi and optional WiMAX3, WWAN,3 Bluetooth and ultrawideband connectivity
• 34mm Express Card slot or 5-in-1 multimedia card reader
• Support for Lenovo’s ConstantConnect and Protect technology that allows users to maximize integration of their BlackBerry smartphone and ThinkPad laptop
• Nearly six hours of battery life
• Supports up to two monitors via a Display Port and VGA connector
• Meets the Energy Star 5.0 criteria for energy efficiency
• Built-in USB/eSATA port

The laptop also marries LED indicator lights to their functions. For example, an LED light indicates whether Caps Lock is off or on. The keyboard also features oversized delete and escape keys. And the space between the keys is smaller, says Critchley, minimizing the chances of trapping sesame seeds between them as the user eats lunch at his or her desk.

Lenovo will also be launching three new docking devices – a port replicator, a mini doc and a mini doc plus. The docs will also work with additional T series devices Lenovo plans to launch next year, the company says.