While waiting for the AD9850 board, Funduino board and PHSNA board I'm having a little fun with my own similar setup. I've been plotting homebrew crystal filters, crystals themselves, and a LPF.
Also thought I'd look for a freeware graphing program that might be better than Excel in some respects. I've downloaded Data Master 2003 and my preliminary opinion is that it has some promise. Got it to graph a .CSV data file that I created.
I had some problems initially with my hardware as my noise floor seemed to be about -50 dBm or so. By rerouting some cables and so on, I can now get down to about -64 dBm, not bad for most of what I'm doing.