IBM Corp will ship its ThinkPad 560 series next week, which at 4.1lbs it claims is the slimmest, lightest notebook on the market with a high quality screen. The line starts at $2,700 for an 11.3-inch dual-scan screen, 100MHz Pentium processor and 8Mb hard drive. At the high end is the 133MHz Pentium ThinkPad with a 12.1-inch Super VGA and 1.08Gb hard drive for $4,100 from July. A 120MHz model is also available and all come with 8Mb of RAM expandable to 40Mb. IBM launched its 4.5lb ThinkPad 701 series in March 1995; the new SVGA model has a larger screen than the 701 and a standard, rather than butterfly, keyboard. The Pentium- based 560 is 1.2 inches thick and is aimed at the corporate or advanced notebook. IBM says recent talk of integrating the Macintosh operating system with the ThinkPad is pure speculation and its current notebook business plan through December includes no such configuration.