NUMBER THREE in the UK supermarket league, Asda, has enlisted The Sun's recently launched free internet service to make its home shopping debut. Asda stores now offer customers free CD-Roms providing access to the service. Initially available on Asda's site are books, music and clothing, with other Asda lines due to come onstream at a later date. Although the supermarket giant has had its own internet site for some time, the joint venture marks its first foray into web-based home shopping. Trailing four weeks behind deadly rival The Sun, the Mirror Group has launched ic24, its free internet service with a claimed 50,000 pre-registered subscribers. MG also claims £1m of advertising support.