Hi.
There is a substantial amount of information regarding computers aimed for video games, video editing and so forth. However there isn’t much pertaining to audio.
Below is the CPU consumption of the computer I use (Pentium 4, 2.8 GHZ, 2 GB of RAM) to design and, test plug-ins on various operating systems.
The charts are based on a fresh boot with an idle time ranging from 1 – 4 minutes.
Windows XP RTM (Non-Service Pack)

Windows 7 RTM (Non-Service Pack)

Windows Vista RTM (Non-Service Pack)

Windows 8 Developer Preview (Non-Service Pack)

If your computer is aimed for audio, you should see no higher than the above RAM usage while idling. If your computer is disabled (using device manager) from Internet, a reduction of 30 – 40% can be acquired in terms of RAM usage while idling.
Note: Spikes in Windows 8, 7, & Vista is based on enabling the Task Manager.
Note: Super fetch is disabled on Windows 7, & Vista
Note: Windows XP & Windows 7 reside on the same hard drive whereas Windows Vista in addition to Windows 8 is on it’s own hard drive.
Although not listed, Windows 2000 will consume 64 MB of RAM while idling off a fresh boot, connected to the Internet.
These figures apply to Windows XP Service Pack 2, 3 in addition to, Windows Vista/7 Service Pack 1 platforms as well.
Greetings from New York!
Sir Elliot