If you haven't upgraded to mIRC 6.2, then you can hide the status windows using /window -h "status window"
Please note that this will hide all of your status windows, and does NOT work in 6.2. The fact that it doesn't work in 6.2 has been mentioned in the bug reports section a few times, and was reported almost as soon as 6.2 was released.
You should only have one status screen for each connection, and, normally you'll only have one connection per network, not per channel that you're in (unless you're only in one channel for each network).
I've tried a number of different possibilities to obtain this same style in 6.2, but, so far, I've had no success. Hopefully Khaled will manage to fix the /window -h command so that it works as in previous versions. Additional note, the /window -h command will hide other windows, it just seems to be failing when trying to hide the status window.