APPLE'S new PowerBook 150 has just arrived in Hong Kong. It is being offered to computer users at a recommended retail price of US$1,399. The PowerBook 150 replaces the PowerBook 145B - despite some improvements, it weighs about 2.47 kilograms. Tim Wheeler, marketing director for Apple Far East, said the PowerBook 150 was Apple's ''most affordable notebook''. Compared with the 145B, the 150 has a bigger display at 9.5 inches (about 24.7 centimetres) and a larger hard drive of 120 MB. Memory is upgradable from four MB to 40 MB. Software available with the new PowerBook includes the PowerBook Control strip, Macintosh PC Exchange, MacLink Plus/ Easy Open Translators, Macintosh Easy Open, PowerBook File Assistant, PowerBook 150 Backup Utility and Calendar desk accessory. Macintosh's top selling ClarisWorks is also included, offering word processing, spreadsheet, database, drawing, painting and communications modules. The new addition to the Apple product line is available from all Apple dealers, including Reptron.