This driver worked with Microsoft Windows 95, Microsoft Windows 98 and Microsoft Windows ME. All diagnostics on the modem worked correctly in all three operating systems and when put to actual use, the modem maintained a stable connection. On this particular computer, the driver went in with no problems. In fact, it was the only driver that went in with no hang-ups!!! Hope this helps someone out there, I know many people are looking for drivers for PC Tel modems and they are hard to find!!!