Capture One Pro is a great tethered capture application. Sadly, there are two major features from the Mac version that just plain don't exist on the PC version. We're an all PC shop, but the first of these two has been enough to make me wish we could switch. This is mostly just an FYI for those thinking about purchasing a machine for tethered capture.
1) The Capture One preview converter: I haven't used this little utility (available for free here: http://www.phaseone.com/Content/Downloads/COforMac.aspx
) but apparently it extracts the adjusted jpg previews from the C1P preview cache at blazing speed. This is great for delivering proofs to a client on set without making them wait for hours as you quickproof.
2) Composition Overlay: Ok, this is clearly a bit more minor than #1 above. On the Mac version, you can import a tiff or jpg to overlay layout art to help with composition. This is great for ensuring you leave space for text on magazine covers tries, for example. I'm not really sure why this simple feature is completely missing on the PC.
There are other features missing from the PC version (see this chart: http://www.phaseone.com/Content/Software/ProSoftware/ProductOverview/FeaturesAndFunctions.aspx
) but these are the two I find myself cursing on a regular basis.