What OS do you use?

[Paprika]

All 5 computers in my house are running Windows 7 Ultimate x64. On my main I have been running 7 since the early beta days of the os, even then was still better than Vista.

Note that it would have been hard to be better than vista :P

[Knives]

My computer just a bit old but im using xp

[foxtrot08]

I am using Windows 7 - Professional Edition

[Mehasaurus]

Windows Vista and Windows 7, depending on how I'm feeling.

[Ex1oN]

Desktop has Windows 7 and ubuntu linux on it.
Laptop has Windows 7.

[petrov1991]

I use W7 mainly. From time to time (because of my work as a DJ) i use Mac too.

[slinkmunkee]

i'm using OS X, on my macbook but i run parelles with windows xp as most of the modding programs are for that os

[NobleScarlet]

Multi-boot here in my Desktop PC with Windows XP Professional 32 and 64-bit and Windows 7 Ultimate 64-bit
My Notebook is running on Vista Home Premium 32-bit...