Now that Microsoft officially admitted its new operating system Vista wouldn't ship for consumers until some time next year (surprise, surprise), companies who rely on a Christmas boom for hardware and software sales are a bit worried. Most of the stories paint a happy picture, but I'm not sure I believe it. If consumers, and businesses buying before the end of the year for tax reasons, have an excuse to delay purchases some retailers and manufacturers will be hurt.If year-end buying just extends into early 2007 (assuming Vista arrives early in the year), the financial hole may not be too deep. But if Vista stretches in the summer, expect all the analysts to start wailing about distressed sales hurting the economy. Personally, I believe you can start worrying about rolling out Vista no sooner than spring 2007. Let the early adopters step in the holes, so you can safely follow a well-marked upgrade path.There's a decent chance big PC manufacturers will drop prices to keep volume up. If so, buying a computer at the end of this year may be a smart decision. Since buying Vista also means, for nearly everyone, buying a new PC, you may want to consider an extended warranty. PC World gives technical product warranties a good look in Are Extended Warranties Worth It?Let me add a reminder about an earlier PC World reference when they checked various tax preparation packages in It's Tax Time. I mentioned that review before, but now it's actually moving toward the forefront of most people's brain now that they've been using the April part of their calendar for appointments next week. Where did I put my extension form?