If you choose a driver like WASAPI, you can set it to exclusive.
ASIO probably does the same by default.
Another typical audiophile option is memory playback.
An interesting experiment is to start the Windows Resource Monitor as soon as possible after a boot.
You see a hell of a lot of activities going on.
After a while they stop and go to sleep.
So as long as a service doesn’t kick in, it is not very likely it will affect sound quality.
Some processes can be very intrusive like anti-virus.
Power saving schemas can have an impact:
http://thewelltemperedcomputer.com/SW/Windows/Win7/TweaksPower.htmDo observe that there are many claims on forums about improving sound quality by minimalizing system activity.
Do observe that almost all of the time none of these claims are backed by any measurements.
BTW: it is not about the bits but about the timing (jitter).