In an effort to standardize its 130,000 desktop computers, the Internal Revenue Service (IRS) is replacing its outdated 486 environment with desktops that will be configured with a minimum 166 megahertz Pentium processor. In addition to getting rid of the old hardware, the IRS will get a new suite of software, known as a common operating environment (COE), which includes Microsoft's Windows NT 4.0 operating system, Office 2000, and Attachmate's INFOConnect. The IRS will also make use of a transitioning software product from Tranxition Corp., called Personality Tranxport Professional, a cost-effective solution for preserving the data and preferences on users' old desktops. The software could save the IRS as much as $29 million over the next year.