Unfortunately the device manager info isn't all that helpful.  It's easier to identify the correct hardware either from your original invoice or with the system configuration tool - just plug in your service tag:

http://support.dell.com/support/topics/global.aspx/support/my_systems_info/en/details?~ck=ln&~tab=2&c=us&cs=555&l=en&lnki=0&s=biz

The results may look a little cryptic, but it's usually fairly easy to ferret out the actual device names (in your case, network (ethernet), audio, and I assume a dial-up modem), or in the worst case you can use the 5-digit part number to search for the correct device name.

Thanks Alexandra_P.
The link in my original message is to Drivers and Downloads for the Dimension 4550 desktop.
From the list I have tried Communications and Audio drivers, but perhaps I did not select the right one for my PC. Therefore I copied the system information for Problem Devices.
I have tried to search the internet with the Vendor/Device/Subsystem identification, but did not find anything that I could use to make the connection between the hardware and the drivers needed.
I also looked at the “What was shipped list” and used the part number in a search and got Not Found.
I no longer have the Resource CD. How or where can I obtain the system configuration tool?
How do I identify the hardware to obtain the correct drivers listed at the Drivers/Download page?

The link I posted was for Dell's system configuration tool, which will tell you the same thing that's on your invoice.

If you'll copy and paste the results from the system configuration tool, I'll try the best I can to help you decipher it.

Thank you. Here's the information you requested. Hope this helps.

System Type: Dimension 4550
Ship Date: 5/21/2003
Dell IBU: Americas
 
 
 
Quantity Parts # Part Description
 
1 1W393 PROCESSOR..., 80532, 2.53, 512K, 533, SOCKET N..., C1
1 M0321 CARD (CIRCUIT)..., PLANAR (MOTHERBOARD)..., DIM4550, NETWORK INTERFACE CARD/CONTROLLERS..., EPPID
1 7N242 KEYBOARD..., 104, UNITED STATES..., SILITEK..., LOW COST..., MIDNIGHT GRAY...
1 6U220 KIT..., MOUSE..., PERSONAL SYSTEM 2..., S69, LOGITECH...
1 8T914 DUAL IN-LINE MEMORY MODULE..., 256, 333M, 32X64, 8K, 184
1 5W416 MODEM..., V.92, DATA FAX..., INTERNAL..., ALUMINUM..., DELL AMERICAS ORGANIZATION...
1 4N567 KIT..., SPEAKER..., 120V, HK206, NMB..., DELL AMERICAS ORGANIZATION...
1 9U159 COMPACT DISK READ WRITE..., 650M, 1, 5.25" FORM FACTOR..., 48X, HITACHI LG DATA STORAGE..., CHASSIS 2001...
1 4U144 CARD (CIRCUIT)..., MULTI-MEDIA..., AUDIO..., SB0243
1 6Y078 DIGITAL VIDEO DISK DRIVE..., 680M, 16X, I, 5.25" FORM FACTOR..., LITEON..., CHASSIS 2001..., V4
1 9P301 CARD (CIRCUIT)..., GRAPHICS..., NV17, FULL HEIGHT..., SECOND..., DIMENSION...
1 5W540 DISPLAY..., FLAT PANEL DISPLAY..., 17, DUAL..., E171FPB, MIDNIGHT GRAY..., DELL AMERICAS ORGANIZATION...
1 7T281 FLOPPY DRIVE..., 1.44M, 3.5" FORM FACTOR..., 3MD, NO BEZEL..., TEAC..., V4, CHASSIS 2001...
1 0J568 KIT..., SOFTWARE..., MS-MNY-2K2, ORIGINAL EQUIPMENT MFGR...., ENGLAND/ENGLISH...
1 0E784 KIT..., SOFTWARE..., OFCXPSB, ENGLAND/ENGLISH..., ORIGINAL EQUIPMENT MFGR....
1 8P472 KIT..., SOFTWARE..., OFCXP-SP1, ENGLAND/ENGLISH...
1 6W678 KIT..., SOFTWARE..., OVERPACK..., WXPHSP1, COMPACT DISKETTE W/DOCUMENTATION..., ENGLAND/ENGLISH...
1 D0837 KIT..., DOCUMENTATON ON FLOPPY DISK..., SOFTWARE..., DIGITAL VIDEO DISK DRIVE..., CYBERLINK..., 4.13C
1 X0770 HARD DRIVE..., 60G, I, 7.2K, 60G/P, HIT-VAN2
 

The list of drivers for the Dim4550 are:

• Intel 845PE chipset driver
• AGP 4X Video Driver
• ADI integrated audio driver
• Intel 82559 Integrated NIC driver
• USB 2.0 Driver
• Microsoft USB QFE Patch

The simple communications device is most likely the modem.  The exact driver to use for that will depend on which model/brand of modem it is (in this case the V.92, DATA FAX modem).

The invoice also lists a Sound Blaster audio card (SB0243) and an nVidia video card (NV17).

EDIT:  Apologies, Larry, I was working this post out in notepad and didn't notice your reply.  It looked to me like the M0321 does not have any integrated audio, so no ADI. 

Between Google and your manual, here's what I get:

Ethernet (Network)

M0321: Motherboard w/NIC

No indication on your list you have anything other than the standard integrated Intel 10/100 controller:

http://support.dell.com/support/downloads/download.aspx?c=us&l=en&s=gen&releaseid=R52043&SystemID=DIM_PNT_P4_4550&servicetag=&os=WW1&osl=en&deviceid=2834&devlib=0&typecnt=0&vercnt=3&catid=-1&impid=-1&formatcnt=1&libid=5&fileid=61613

There's also a 10/100 diagnostics utility listed there if you want it.

Multimedia Audio

SB0243 is a Dell OEM version of the Creative Soundblaster Audigy 2 PCI sound card.  That sound card should have come with a driver/application CD; Dell doesn't post drivers for the Creative cards.  If you don't have it, here's the generic Audigy 2 driver from Creative, but as the Dell versions of Creative's cards often use custom drivers I can't guarantee it will work:

http://us.creative.com/support/downloads/download.asp?MainCategory=1&nRegionFK=&nCountryFK=&nLanguageFK=&sOSName=Windows+XP&region=1&Product_Name=Audigy+2&Product_ID=149&modelnumber=&driverlang=1033&OS=10&drivertype=0&x=15&y=12

PCI simple communications (modem)

SW416: Is a Conexant RD01-D270 V92 modem.  I haven't had much luck yet figuring out which of the multiple available Conexant drivers it is, and I'm hesitant to guess right now.   

Video NV17, 9P301 = Nvidia GeForce 4 MX420 .  XP frequently puts in a working generic driver for video; if you want you can get Dell's version for better functionality, or with the Nvidia cards you usually have no trouble using more updated versions available from www.nvidia.com .

http://support.dell.com/support/downloads/download.aspx?c=us&l=en&s=gen&releaseid=R59536&SystemID=DIM_PNT_P4_4550&servicetag=&os=WW1&osl=en&deviceid=2836&devlib=0&typecnt=0&vercnt=3&catid=-1&impid=-1&formatcnt=1&libid=6&fileid=73001

I think I've figured out which Conexant driver it is - it appears a couple are duplicates of the same version, another is non-US (if you happen to be in Europe or New Zealand, post back) , one is just an older version, and one is an application, not a driver.  Bleh.

http://support.dell.com/support/downloads/download.aspx?c=us&l=en&s=gen&releaseid=R58827&SystemID=DIM_PNT_P4_4550&servicetag=&os=WW1&osl=en&deviceid=1538&devlib=0&typecnt=0&vercnt=1&catid=-1&impid=-1&formatcnt=1&libid=20&fileid=71473