Can I ask some questions?
I have returned two core duo minis due to this issue. Every demo unit I've tested at the stores has wireless issues. Macintouch is full of reports of how these features are broken.
I've given up on them, at least until Apple makes a statement and recall on units. But if your unit is working perfectly, maybe they fixed the problem....
I have an iMac G5 with Airport and Bluetooth. The battery life is short on my mouse, but the keyboard goes for a very long time. The only Airport issue I have is that sometimes it doesn't automatically connect on startup and I have to click it on. Range and stability are fine.