New tests have revealed that Windows XP with the beta Service Pack 3 has twice the performance of Vista, even with its long-awaited Service Pack 1.

Vista's first service pack, to be released early next year, is intended to boost the operating system's performance. However, when Vista with the Service Pack 1 (SP1) beta was put through benchmark testing by researchers at Florida-based software development company Devil Mountain Software, the improvement was not overwhelming, leaving the latest Windows iteration outshined by its predecessor.

Vista, both with and without SP1, performed notably slower than XP with SP3 in the test, taking over 80 seconds to complete the test, compared to the beta SP3-enhanced XP's 35 seconds.

Vista's performance with the service pack increased less than 2 percent compared to performance without SP1--much lower than XP's SP3 improvement of 10 percent. The tests, run on a Dell XPS M1710 test bed with a 2GHz Core 2 Duo CPU and 1GB of RAM, put Microsoft Office 2007 through a set of productivity tasks, including creating a compound document and supporting workbooks and presentation materials.

"Frankly, the world wasn't 100 percent ready for Windows Vista"

A year after its launch, only 13 percent of businesses have adopted Vista, according to a survey of IT professionals.

XP has proved to be more popular than its younger sibling, with the first six months of U.S. retail sales of box copies of Vista 59.7 percent below those of XP's in the equivalent period after its release.