Currently, I use the standard Windows 7 calculator in "Programmer" mode, and it's great. It does everything I need... except it has no support for unsigned integers. Which is all well and good if you are dealing with 8, 16, or 32 bit integers; just leave it in quad word mode and you won't have any two's compliment problems, but there is no way to represent an unsigned 64 bit integer.
To be clear, I am looking for a windows program, not a chrome extension or simply "use google". The software must support bitwise operators and handle unsigned/signed integers of at least 64 bits in size, and at least hexadecimal, binary, and decimal display. Support for floating point numbers is not necessary, but would be awesome.