Drivermax caused me more problems than it solved. The manufacturers' websites have consistently proven the best source for me.
I've found that Win 7 eventually finds all the drivers it needs, although it may take a day or two and several "reboots" to achieve that.
I suspect LR had his speakers muted - it does have that effect. I have the taskbar icon, so I can see if the little speaker has a red line through it.
I also have a nifty utiity called "Automuter" which turns the speakers off at 10pm and on again at 8 am.