Escape Medical Viewer is a good DICOM product, built upon QuickTime technology and is available on both the Mac and PC platforms. As a commercial and cross-platform product, it is an easier sell to IT Departments than an open source application.
EMV is a good choice for Mac users working in a mixed platform Radiology Dept. IT in most hospitals wants ONE app- not a hodgepodge. EMV allows PC Radiologists and Mac Radiologists to have the same application while using the computer of their choice.
The other great advantage is the commercial support available that is not replicated on most open-source software. OsiriX is a great app that is getting better all the time, but many IT Admins or Imaging Directors will balk at the lack of support.
If you can find an Apple Value Added Reseller that will support OsiriX, go for it. Otherwise, you will find a great deal of resistance from Administration, IT and the Radiologists. EMV is also more G4 friendly than OsiriX, and would be a good choice for laptop use on a PowerBook for ON-Call image review.
For Workstation (read G5 with a good video card and a lot of memory) use, OsiriX. For mobile image review on a G4, use EMV.