Today, Microsoft announced that it has opened registration for its Windows 8 upgrade promotion. Anyone who purchased a Windows 7 machine after June 2nd of this year can register from now until January 31st of next year to upgrade to Windows 8 Pro for just $14.99 — if you miss the registration period, you'll have to pay full price for the new software when it comes out. The offer was originally said to be available in 131 countries, but Microsoft now reports that the deal is running in 140 countries — the full list can be found at windowsupgradeoffer.com. If you're eligible and as excited as David Pierce is about Windows 8, you should head on over and sign up, it's surprisingly painless.