Microsoft Corp said on Wednesday it is releasing the code for Windows 7 to PC manufacturers, keeping the software company on track to have machines running its new operating system in the stores by late October. The move means Hewlett-Packard Co, Dell Inc, Acer Inc and other computer makers can start to load up new PCs, laptops and netbooks with the operating system, the successor to the unpopular Vista. Both Microsoft and the manufacturers are hoping the full launch of Windows 7, scheduled for October 22, will help lift PC sales out of the slump caused by the global economic downturn, and give the holiday shopping season an extra lift. Manufacturers have been testing early versions of Windows 7 for several months, but this week marks the release of the “gold code,” according to a Lenovo Group Ltd executive, referring to the software industry jargon for the finished product. PC makers no longer have to fly discs in helicopters to their manufacturing plants, as the transfer is now done electronically. But it still marks a dramatic day as manufacturers hustle to get new products into stores in time for the release date.