What is your favorite operating system?

my favorite is Windows 7

I'm still using XP SP3. I tried Vista & 7 and din't like either tho 7 is better than Vista.

Windows 7 x64 FTW

Windows 7

Win7

Win 7 - god bless 64 bit!

My favourite would be whatever the newest Windows OS is, in this case Windows 7.

Linux. Is there anything else?

Windows 7

Win 7 64bit