Hillard Sterling, an attorney at Freeborn & Peters LLP in Chicago, said that VMware would have to "show real, proven barriers to competition. And even if VMware could satisfy that burden, it faces a separate, and potentially more difficult, battle of getting the remedies it wants."

Bruce McMillan, manager of emerging technologies at Solvay Pharmaceuticals Inc. in Marietta, Ga., is using Windows servers in a VMware virtualized environment. McMillan has read the white paper posted by VMware and said he thinks it "is there as a means to help educate people about what's going on."

But he said he hasn't run into the issues outlined in the document. And just because Solvay is using virtualization technology, McMillan added, "it doesn't mean we're going to buy less [Windows] licenses."