Comical is a portable CBR and CBZ viewer written in C++ using wxWidgets. It supports multiple image formats and uses high-quality image scaling algorithms to fit pages onscreen.
Having tried Comical and ComicRack on a Win7 64bit machine I find them both to be horribbly slow, IF you can get them to open at all. Cdisplay and Sumatra both open lightening fast, don't require netframework nonsense. Come on, these comics are compressed JPGs. What in the world do we need netframework for in these softwares? Sumatra is even offered in a portable version, works great. No, they don't have a gazillion features. But hey, I just want to read a comic book... And for what its worth, a 152MB .cbr, opened with 7ZIP, converted to PDF with acrobat opens ten times faster than Comical or ComicRack as well.