A convincing twin of Darth Vader stalks the beige cubicles of a Silicon Valley office, complete with ominous black mask, cape and light saber.

But this is no chintzy Halloween costume. It’s a prototype, years in the making, of a toy that incorporates brain wave-reading technology.

Behind the mask is a sensor that touches the user’s forehead and reads the brain’s electrical signals, then sends them to a wireless receiver inside the saber, which lights up when the user is concentrating. The player maintains focus by channeling thoughts on any fixed mental image, or thinking specifically about keeping the light sword on. When the mind wanders, the wand goes dark.

Engineers at NeuroSky Inc. have big plans for brain wave-reading toys and video games. They say the simple Darth Vader game - a relatively crude biofeedback device cloaked in gimmicky garb - portends the coming of more sophisticated devices that could revolutionize the way people play.

Technology from NeuroSky and other startups could make video games more mentally stimulating and realistic. It could even enable players to control video game characters or avatars in virtual worlds with nothing but their thoughts.

Google has removed paid links that advertised seemingly legitimate Web sites but actually tried to install nefarious programs on PCs.

The links were displayed as “sponsored links” after visitors entered specific queries into Google’s search service. Clicking the links would ultimately go to a legitimate site, but by way of another site that attempted a “drive-by installation” of password-stealing software. Miscreants placed the links using Google’s AdWords service for advertisers.

“Google identified and canceled AdWords accounts displaying ads that re-directed users to malicious sites,” a company representative wrote on a corporate blog on Thursday.

The malicious links appeared after people searched for terms related to the Better Business Bureau and cars, according to Exploit Prevention Labs, a security company. All the paid-for links masqueraded as legitimate sites and redirected Google users to the actual sites after sending them to smarttrack.org, which served up the malicious code, Exploit Prevention Labs said.

Microsoft is expected to show a new friendliness to the open-source community by unveiling plans to release the source code to a part of its Silverlight technology at MIX 07 next week, according to sources familiar with the company’s plans.

Sources said Microsoft will also release a beta of Silverlight, a recently unveiled browser plug-in that allows Web content providers to offer a rich video and interactive media experience from directly within Web sites. The technology leverages Vista’s new graphics framework, Windows Presentation Foundation (WPF), and Microsoft is promoting it as a direct competitor to Adobe Systems’ Flash tool and delivery mechanism for rich multimedia content on the Web.

The Chilean government wants Google to fix its Earth geographical search program that places a village named after Chilean independence hero Bernardo O’Higgins in Argentina.

The satellite image shows Villa O’Higgins, a tiny hamlet 1,000 miles south of the Chilean capital, Santiago, on the Argentine side of the border.

“Chile has asked for this to be rectified, and it can only be hoped they do it soon,” a Foreign Ministry spokesman in Santiago told Reuters on Saturday. He declined to say when the complaint was filed.

Chile and Argentina share the southern cone of South America, where the border between the two nations runs through a complex landscape of islands, fjords and mountains.