Microsoft has restricted access to the beta version of Windows Vista after fears that the sheer volume of downloads could bring down the internet. 

Longhorn blogger Robert McLaws said that Microsoft revealed in an official Q&A that unrestricted Vista beta downloads could topple other services. 

"If we pushed out bits any faster there would be a measurable impact for the internet," McLaws said, quoting Microsoft at the briefing.

"We are literally saying that if we increased our bandwidth any further there is a possibility of taking down the internet. People might have problems with World Cup viewing, etc."

Microsoft insisted that it had anticipated the demand, but that downloads had reached the threshold of what the internet can bear.

The two downloads of the Vista beta software include a 32-bit version at 3.5GB and a 64-bit version at 4.4GB.