You can usually find the manufacturer's number in the operating manual. For the record, Apple's Macintosh operating system is Y2K compliant. If you don't store financial or date-sensitive information on your computer, there shouldn't be a problem if you don't update your computer by midnight. If you do use your computer to keep financial records or do your taxes, first make back-up those files. Then, update your computer before midnight.
Local utilities say they are prepared and expect no problems.
But if for any reason you experience a power outage, use the following numbers to report the problem. Leave a light on to signal when power is restored. Again, no problems are expected. But if you do experience an outage, call the appropriate phone number before. If you simply want to ask company representatives what they recommend in advance, call one of the non-emergency numbers.