CAMBRIDGE, Mass. -- Hesitant to make the leap to Vista? You're not alone, according to new research from Forrester Research. A survey of 2,104 hardware decision-makers at North American and European large, small and medium businesses found that Windows XP continues to dominate the PC operating system landscape and that fully 45% of the respondents did not know when they would switch to Microsoft's newest platform. The think firm said it expects the release of the first major service pack this year to be among the factors that will speed up adoption.