Microsoft's MSN division has started testing a Web-based RSS aggregator, a move it's making to stay with rivals like Google, Yahoo, and Ask Jeeves.

The new Start.com page is clean and advertising-free, includes categories of pre-set RSS (Real Simple Syndication) feeds, and lets users enter both RSS- and Atom-formatted feeds to customize the aggregate.

The Web aggregator is tied to MSN Search, and also saves search histories.

In January, MSN added RSS aggregation within the My MSN personal home page, and a month later, followed that by allowing MSN Search results to be saved as an RSS feed.

The RSS project is one of two at the start.com site -- the other is a Web-based bookmark collector and storage utility -- that is loosely associated with Microsoft's Sandbox, where the Redmond, Wash.-based developer deploys early looks at MSN technologies.

"This site is not an officially supported site. It is an incubation experiment and doesn't represent any particular strategy or policy," disclaimed Microsoft on the site.

The aggregator, available for testing here, works with Firefox, the open-source browser that's been nibbling at Internet Explorer's market share, as well as Microsoft's own IE.