What is the actual sound chipset? There are only a few sound chipset makers in the world... amongst them are C-Media, Realtek, ADI, Sigmatel. If you have Everest installed then it should identify your sound chipset and offer a possible link to the driver. Intel is only the main chipset maker and has nothing to do with the actual sound chipset.
USB support is included with the XP OS. You won't get USB 2.0 support unless you install Service Pack 1 or Service Pack 2. Without the service pack installed, you will only get USB 1.1 support. However, bear in mind that in order to get USB 2.0 compatibility, you must have a USB 2.0 controller. The service pack will not make a USB 1.1 controller into a USB 2.0 controller.
You said you downloaded the driver from Intel that eMachines suggested. Did you go the next step and install those drivers? You didn't say. If you haven't already done so, I suggest you follow eMachines advice and install those drivers recommended.
And if you can ID your sound chipset, we will be glad to look for any driver that might be available for it.
Another thing I don't understand.... why did eMachines not have drivers available for a product in which they sell? There's where the support should come from.