The Windows 95 ThinkPad 240 notebook weighs around three pounds and is in the same class as the Sony Vaio Z505 notebook.
The ThinkPad 240, however, is in the price range of the Sony at about $2,000 with a 300-MHz Intel processor and 6.4GB hard drive.
But unlike Sony, which targets sophisticated consumer buyers, IBM is aiming more for corporate users. IBM will also offer Windows NT, which many large businesses use, in addition to Windows 95 and 98.
IBM will also provide a set of "enterprise tools" that allow a notebook to be used in a networked corporate environment.
Big Blue has been offering ultralight sub-notebooks in Japan for years but, until now, had avoided bringing these designs to the United States. But competition is now heating up in this market.
Compaq is also slated to bring out an ultralight Armada model later this summer and just released a sub three-pound Aero 8000 notebook which runs Windows CE and looks more like a small Windows 95 portable than a typical Windows CE device. This is priced at just less than $1,000.
Recently, IBM has been bringing out a number of diminutive devices. Last month, IBM introduced the WorkPad z50 based on Microsoft's Windows CE operating system. The z50 is a "Jupiter"-class Windows CE device, which means that it looks a lot like a shrunken version of a ThinkPad notebook.