irqbalance is off

[compdoc]

I notice on a fresh install of 11.04, services like irqbalance and acpid
(and others) are not enabled to run at boot. I will be using this quad-core
box as a file server, and to run qemu-kvm guests.

I suppose if these services were needed they would have been enabled by the
installer when I installed qemu-kvm, but I'm curious because irqbalance
tends to be running on other servers I have.

Is it useful or needed?