I saw an interesting piece discussing Microsoft's woes with their band-aid fix for playing multi-media while on a loaded network. From the description of the scheduling work around it does seem like a school boy error, you just can't fix performance issues by tweaking priorities.
Although Linux is still meant to be trying to fix interactivity issues it's been a long time since I've noticed any conflict between my media players and other tasks such compiling. About the only performance issue I still come across is "morning swap syndrome" when a lot of overnight activity on your machine can lead to it taking a while to swap your open apps back into main memory.
Of course it's not all totally green on this side of the OS fence. Of the two wireless interfaces on my laptop the old Lucent Gold Card does utilise a rather high amount of processor time when doing large copies. It doesn't interfere with the desktop performance but it is a little disappointing. Looking at /proc/interrupts I can see it would certainly benefit from being able to support a pure poll mode although I suspect the main bottle neck is just the copying of data across the PCMCIA/PCI bridge. It is not yet enough of a bug factor to make me dig into the code though.