A leaked memo has revealed that Best Buy will begin pre-selling Microsoft’s Windows 7 operating system on 26 June in the US.

The retailer confirmed late last week the date people can start buying Vista-based computers and subsequently qualify for a free upgrade to Windows 7, when it lands in October.

Engadget has published a copy of the memo here. It outlines prices for upgrade versions of Windows 7 Home Premium ($49) and Windows 7 Professional ($99), both of which will be available via the Best Buy website.

It looks as though the prices listed may in fact be promotional offers, as according to the memo the program will only run for 16 days.

“Microsoft is launching Windows 7 in mid-October 2009. This new operating system isn't just a ‘Vista that works’ program — it’s a new operating system with improved productivity, functionality and creativity that uses less computer resources,” opined Best Buy, which seems happy to note what a big fat failure Vista has been since its lead balloon launch in 2006.

Meanwhile, Microsoft has confirmed to The Register that it has no plans to slap Vista Capable-style stickers on machines worthy of an upgrade from the unloved OS to Windows 7.

The company has ditched those marketing tactics after a heap of bad publicity and a lengthy lawsuit that continues to limp along in the US.

Microsoft said in an official blog post last week that it was readying its Windows 7 upgrade option program, but didn’t spill any further information.

When asked about the specifics of what constituted a “qualifying PC” for the upgrade program, Microsoft was unable to tell El Reg because, according to a Redmond flack: “This has not yet been defined.”

Despite that lack of essential knowledge, the software giant was at pains to note that any computers that had Vista loaded would be capable of running Windows 7 too.

Microsoft’s official date for Windows 7 to hit the shelves is 22 October. In the meantime, anyone eyeing up a computer will be pondering whether to postpone a purchase. Unless they’re a secret Vista lover, that is. ®