Windows is in another of its periodic phases of development, where most old software won't work with the new-look Windows 8, so it is worthwhile considering an upgrade.
Through to the end of January, the court-designated abusive monopoly is offering quite a deal, to upgrade any recent Windows version to a Pro version for $39.99, or roughly 1,250 baht in real money, depending on money markets and your credit card company.
I am not (yet) a huge fan of Windows 8. But unless you are ditching your PC or laptop completely, this new-look OS is what will run new software and handle smartphone apps, while older versions including XP and Vista certainly will not.
You can try the process for free. A Microsoft app will test your current machine, advise you of what you will have to do to upgrade, and walk you through _ if you want _ payment and the 2GB download of the new operating system. This is definitely a bargain in price and convenience for anyone who actually wants it.
Even today, top websites like Amazon.com and Microsoft.com are offering this upgrade at around double the price. To get the bargain, you have to go through Microsoft's own bargain page _ not hard to find at all, but still easy to miss.
The English version of this deal is at tinyurl.com/a4f3xob.
The exact, same deal in Thai is at tinyurl.com/bjyod5q.
If you are trapped by your browser in the wrong language, do this. At the very bottom of the Microsoft web page, on the left side, there is a small icon of a gear. Click it and you will get a page with the list of Thai, English and all 60 other supported languages, which seems adequate.
One other important point. There is no mention of this by Microsoft, but so far as I can see this is not an amnesty. If Microsoft thinks you aren't currently running "authentic" Windows XP, Vista, Windows 7 or Windows 8, it probably will not allow the offer. This is an upgrade for "real" Windows users.
Payment is by credit card. This can range from maddening to impossible when dealing with American companies. Getting their software to accept the US-centric billing addresses for Thailand can be a trial. This time, my Bangkok Bank card worked for me just fine, first time. Next time, who knows?
If online purchase fails, you can get this deal by mail for an extra, exorbitant $15 (about 460 baht). But don't do this except in an emergency because the download allows you to make your own DVD, thumb drive or other installation media. Having the original is always a good idea but there is no reason to pay such an outrageous amount for it when you can do everything online.