You first need to explain what you're trying to do, but HEX to Binary is EXTREMELY easily to do, as they are very close to been the same thing (which is why HEX if used).
For those of you that use Vista, there's a sidebar addon that I use called calculatorium which is a very nice scientfic command line style calculator that can be used to convert between hex/dec/octal long/short notation and has many built in functions.
Of course, number formats are completely interchangeable - but I would suggest that's a VERY bad choice to make for this particular declaration, as the binary version only confuses (each decimal, or hex, number refers to a single bit - the binary version looks like it's two bits).