I want to reinforce what Ted Cline said about why we want to use GNU Radio in Amateur Radio Astronomy in last GNU Radio Group hosted by Andrew.
GNU Radio does the buffer management and scheduling of processing for us, A flow graph sends data from one block to the next but who manages this coordination for us? Gnu Radio does this for us in multiple processes using our new multi-core hardware
Suppose you have data arriving from your sdr at a very fast rate... you need to buffer it and make it available to your collection software in an orderly manner. GNU Radio software will for do this for you.
GNU Radio uses compiled C++ code to speed up the heavy lifting of digital signal processing... such as FFT's and Infinite Impulse Filters...
It is cool stuff try it.
Stephen