That's a beauty.
.EXR files can be opened in Photoshop CS, HDRShop (commercial version), and many other 2D programs. If you have a program that opens .HDR files but not .EXR files, then you may be able to find an EXR to HDR converter somewhere. There are others on this forum that know more than I about how to use EXR data for post-processing.
Matt