I have been very happy with Mister_E's Pic MultiCalc program.

I might give yours a try, but one thing I see missing is the "quick selection" of standard built-in clock frequencies, such as 1 & 2Mhz, and 31, 125, 250 and 500kHz. These are great clock speeds to use when you are trying to save battery power. I understand I could enter it manually, but personally, I use these lower clock frequencies far more often than I use anything over 8MHz.