Multimedia Audio Controller / PCI Simple Communications Controller

I think you need to download and install this: http://www.dell.com/support/drivers/us/en/19/DriverDetails/DriverFileFormats?DriverId=K4JGP&FileId=2731107785

Reinstalling Windows won't help because the drivers you need aren't on the disc, and XP, unlike 7, won't seek out and download drivers automatically.

I'm not sure what the PCI Simple Communications Controller is; if you can get the vendor and device IDs from the device properties in Device Manager, you can look up the device here: http://www.dell.com/support/drivers/us/en/19/DriverDetails/DriverFileFormats?DriverId=W293Y&FileId=2731089240

When you reinstall the operating system on a Dimension 4600, it is necessary to begin with the chipset driver.  Otherwise Windows can't see everything that the chipset supports.  Dell has a guide to reinstalling Windows which can be examined here:  Restoring or Reinstalling Windows on a Dell.  A full installation is covered in the third option on that page.  Pay particular attention to the instructions on installing drivers.

If you still have the Dell Resource CD that should have been shipped with your computer you can use that to determine which drivers you need and also install them.  If you would prefer the most recent versions of the drivers you can find them on this page, although you will need to identify those you will need yourself:  Dimension 4600 Drivers.

The PCI Simple Communications Controller is usually a telephone modem.  If you still need this you will have to figure out which modem you have.  The driver for this was normally supplied on a separate disk and is not usually found on the Resource CD.

I doubt the chipset drivers are an issue in this case, but the OP can go to Intel to get the latest version: www.intel.com/.../inf

If the chipset drivers are not installed, there will be other devices lacking drivers, not just the audio and peripherals. You will see this problem installing XP with a new mainboard (like a Socket 1155) because it didn't exist at the time the XP install images were generated, but for an older machine like a 4600, the core chipset drivers will be on the disc.

The problem in this case is that the 4600 has Conexant audio and possibly a Conexant modem, neither of which have drivers on the XP CD. And, being XP, the drivers must be sought out and installed manually. The OP may want to try installing the driver for the Conexant modem, as that may be the "simple communications device": www.dell.com/.../DriverFileFormats

It's true that XP appeared in 2001, but there were several subsequent releases. Perhaps my experience is colored because I'm using an SP2 image I acquired in the summer of 2005; it may very well be that if someone is using an older image with fewer drivers they will encounter the problems you describe. And thanks for pointing out that I had the wrong audio link; I have updated it.

If the OP can get onto the Internet, they can go to the Intel download site and use Intel's online chipset utility to identify and install the latest drivers for their chipset: www.intel.com/.../inf

The PCI Simple Communications Controller may be an old-fashioned (Conexant) modem, as I used a 3000 from 2005-07 that had one of those preinstalled. In 2005, many folks were still on dial-up.

XP is quite resilient and I've been able to move an install I created in 2004 for an Athlon 32-bit over to several newer chipsets, with the latest being a Core i5 Socket 1155. It shouldn't be necessary to reinstall the OS because a step was missed; if the machine can't get to the Internet, the chipset drivers can be download from Dell or Intel and installed over top of the existing ones.

I believe you are mistaken on this one.  Windows XP was released in 2001, while the Dimension 4600 didn't appear until 2003.  People who attempted to install the sound drivers on this and other computers of this era had difficulty getting the audio adapter, among other things, to install if they missed installing the chipset driver.

The modem may indeed be a Conexant, but this has nothing to do with the audio as it is a stand-alone expansion card.  Unless the computer was ordered with a Creative sound card, the audio is Analog Devices ADI 1980.

Sometimes it is helpful to know the history.  I owned several Dimension 2400's that were ordered around the same time that the Dimension 4600 became available.  The Windows XP CD that was delivered with them contained Service Pack 1a, which I believe was released in late 2002.  I know for a fact that it was necessary to install the chipset driver for the Dimension 2400 with that release as otherwise the ADI driver would not install.  Service Pack 2 was released in October of 2004; that release might have had an update for the 845 and 865 chipsets, but I've never seen the direct evidence for it.  I do know that Service Pack 2 contained the drivers for the PCI-Express video that was becoming more common at that time.

With regard to the Intel chipset utilities, there is not usually much advantage to using a version later than the file posted in the Dell support page for the computer in question.  Nearly all the updates in the later versions are to accommodate newer chipsets, the problems having been taken care of by the time Dell quit posting new versions.