Wi-Fi Softwares

I’m looking for an easy FREE way to scan the various wifi channels for interference (1-11) and measure the noise floor. I can’t afford a spectrum analyzer, especially when I’ll only be using it once to optimize my home network.
I believed the easiest way was to use NetStumbler, and set my router to each channel — then look at the SNR graph. Unfortunately, it won’t work on Windows Vista.
What’s the easiest way? Is there a equivalent program that can run on Linux (Ubuntu)? Whatever it is must be user-friendly because I’m primarily a Windows user.
My laptop has an Intel 3945abg wireless adapter and runs Windows Vista. I have an Ubuntu 8.10 CD but don’t know what I’d be looking for and NetStumbler can’t run through WINE.

Tags: NetStumbler, network scanning, Ubuntu, Windows Vista