Before you know it, January 2007 will be here. That's when Microsoft says its new operating system, Windows Vista, will be released to consumers. (It is expected to be ready for businesses in November.)

If you're thinking of buying a new computer before then, you will want to consider what you'll need to upgrade, if that's your plan.

Microsoft promises Vista will be much more secure than Windows XP.

All the new features are going to require lots of horsepower. Problem is, it's not clear what "lots of horsepower" means. Microsoft has not yet issued formal system requirements for Vista.

So, what's a new computer buyer to do? You can get around this issue by shopping carefully, but you're probably best off waiting. If you buy a computer in January, it likely will come with Vista.

Unfortunately, not everyone can wait. Dribs and drabs of information have leaked out about system requirements. Keeping in mind that things could change, here's what we think we know:

Processing. Microsoft says you need a "modern CPU." It does not define that but links to the AMD and Intel Web sites. Given the information on those two sites, it appears most of their chips are acceptable. So, essentially, the microprocessor is not an issue. Buy a computer with an Intel or AMD microprocessor, and you should be fine.

Memory. This is more critical. The minimum memory requirement is 512 megabytes of RAM. That sounds like a lot, but it is probably inadequate. You should double that, to 1 gigabyte. And that is if you use your computer for only word-processing, e-mail and Web surfing.

To be on the safe side, I'd go for 2GB of memory. That is excessive for Windows XP, but even XP machines should be able to handle 2GB.

Graphics. You can expect Microsoft to make a big deal of Vista's new graphical interface. But you don't have to use it. Vista's new bells and whistles can be turned off to work better with budget graphics systems.

At a minimum, your computer needs to support DirectX 9, a Microsoft standard. It also needs at least 64MB of system memory dedicated to graphics.

However, to get the full wow factor of Windows Vista, you'll want a more powerful graphics system on your computer. You'll want a video card with at least 128MB of memory. Alternatively, built-in video systems will need at least 128MB of dedicated memory. That's another reason to buy 2GB of system memory.

Hard drive. Vista will take more space than Windows XP. But, given the size of today's hard drives, that shouldn't be a problem.

Of course, you don't have to upgrade to Vista. Microsoft will spend a fortune promoting Vista. Expect it to proclaim that Vista takes computing to a whole new level of fun. That's doubtful — Vista is just an operating system. It's like going nuts over a new hammer.

Windows XP is a stable and reasonably secure operating system. So you can continue to use it. Eventually, new software will not be made for XP, but your computer will likely collapse and die before that happens.