In the wake of Apple's announcement that it has acquired Emagic, and the subsequent discontinuation of development of Emagic's Windows line of audio software several companies have come up with "cross-grade" offers:
Logic to Steinberg Cubase SX ($299)
Logic to Cakewalk SONAR ($199) or SONAR XL ($299)
EXS24 to Speedsoft VSampler PRO (€40) (There's also a screenshot /animation of the forthcoming VSampler v3.0 on that page)