I cannot speak to the Room EQ Wizard software but I do have XTZ. I used it to measure my room and also my speaker response in anticipation of getting an equalizer or room correction device. I also wanted to see the before and after results of the Audyssey MultiEQ of my Denon AVP processor. Having read up on the dos and don'ts of equalization, I was curious to know what the Audyssey was doing in both the frequency and time domains.
I use XTZ on a macbook pro running VMWare Fusion 3 and XP. The odd thing is that when I recall past measurements, especially for the FR and decay plots, the software crashes quite often, more than half the time. However, it relaunches quickly and I keep going.
I imagine that if you discover a room mode you might be able to place acoustic panels in the usual, suspect places (corners etc) and see the effect. This is, in fact, my next move- I am waiting for some bass traps to arrive from Gik Acoustics.