(Reuters) - Microsoft's release of its new Windows 7 operating system is expected to increase demand for personal computers only slightly, Chief Executive Steve Ballmer told journalists in Munich on Wednesday.

"There will be a surge of PCs but it will probably not be huge," Ballmer said in answer to a question at a news conference about the likely effect on the market of the new system, which will replace the unpopular Vista.

Major new software updates from Microsoft, whose Windows operating system runs about 90 percent of the world's PCs, are in general eagerly awaited by computer makers who hope for a sales boost.

However, in a survey of more than 1,000 companies released by ScriptLogic in July, six in 10 companies said they planned to skip the purchase of Windows 7, partly due to spending cuts and partly over concern about compatibility with existing systems.

Ballmer reiterated he saw the technology sector returning to growth only slowly, and said it would take time to reach pre-recession levels.

Windows 7 will be generally available on October 22, far earlier than originally planned.

(Reporting by Jens Hack; editing by Simon Jessop)