Reuters - David Daoud ran into trouble when he started using Vista, the new version of Windows that Microsoft Corp. and PC makers have spent millions of dollars advertising since it came out six months ago.

He said it short-circuited key software programs he counts on: Quicken for balancing his checkbook, Lotus Notes e-mail and a networking program that connects his home to the office. His Sony camcorder also doesn't communicate with the PC properly.

"Basically they don't work," said Daoud, a computer industry analyst with market research firm IDC.

Such problems are part of the normal growing pains that come with every major upgrade to the Windows operating system.

To ease those pains, some consumers are seeking out machines equipped with the more compatible Windows XP. That's prompted some PC makers and retailers to give the older operating system more room in their product lines.

Hewlett-Packard Co. and Dell Inc. recently started selling XP machines on their Web sites. Lenovo Group Ltd. and Toshiba Corp. also offer similarly equipped machines.

Microsoft has done its best to get Vista off to a strong start, making it compatible with more than 2 million different types of hardware.

The effort seems to be paying off. The company late on Thursday reported quarterly revenue of $13.4 billion, up 13 percent from last year, citing help from strong Vista sales.

Microsoft says most people using Vista are pleased with it and that nearly all software and hardware is compatible. 

Still, some companies have been slow to respond to Microsoft's call for upgrades. Consumers have taken note.

Craig Rabe, owner of the Computer Cafe, an independent computer store in Arlington, Massachusetts, says he received so many complaints about Vista after it was launched in February that he stopped selling machines loaded with the software.

"People came back and said, 'Please, will you take this off and replace it with XP," he said.

ALL THINGS TO ALL PEOPLE?

The Massachusetts Institute of Technology is advising incoming freshmen to buy PCs loaded with Windows XP.

"XP is still fully functional. It's what people are familiar with," said Jon Hunt, who made the decision for MIT. But he expects MIT will soon start supporting Vista.

Among retailers, CompUSA says it has the widest selection of XP machines, something it plans to tout during the busy back-to-school sales season.

Circuit City Stores Inc. offers nine XP models on its Web site. Best Buy Co. does not carry XP machines.

The Windows User Group says Vista is an "awesome" system and all of its employees use it. But the company, which provides technical advice on Windows and runs online communities, cautions that the switch can be uncomfortable.

"My father-in-law, my niece, my accountant -- they all have computers running XP now. If they put Vista on top, not everything is going to work," said vice president Joel Diamond.