WinXP32 – Annoyed at 1GB of RAM touching itself while the other 3GB worked like dogs.
Ubuntu – Happy at all 4GB being available… before finding out the ATI HD4870 support is buggy causing video output to flickr during playback. Also would not play WoW nicely in WINE (which made me stab random people).
Vista64 – All 4GB available. Full HD4870 support with stupidly low framerate. Dual monitor spanning removed from Vista due to changes to the core engine resulted in more people being stabbed. Has no switches to disable tcp_ackfrequency and tcp_nodelay resulting in people being hit with blunt objects.
WinXP32 – Happy.
(Looking to try out XP64 though…)