One last attempt...driver help needed!

I posted to this forum a number of days ago. I am so frustrated at this point and don't now what to do since I can't talk to Dell without a $49 fee (for a $20 part). :( I'm going to make one more attempt to solve this issue and then I surrender, once and for all.

Could someone please help me locate the drivers for a DUB-E100 USB 2.0 Ethernet Adapter? My system warranty is up so technical support won't help. The drivers from the manufacturer's website don't work and Dell Tech Support says that I need to download the drivers directly from them (although they won't tell me how to get them). Since the product won't install properly, a system scan doesn't see the product and doesn't list the drivers for my service tag number with a list of all my computer's components. I have a Dell Dimension 8400 with an Intel Pentium 4 Processor 570 (3.8 GHz). I am running Windows XP with Service Pack 3. I purchased this part because I have had the internet connection dropping off intermittently for some time. I will be surfing the web and then a window will open stating that a network cable is unplugged (it isn't) and my internet connection will be gone. Without touching anything, it will come back on its own sometime later. I contacted my internet provider and had the modem and cables replaced. I still have the same problem. They say the problem is with my computer. Over the Christmas break I installed a new hard drive, upgraded memory and reinstalled the operating system. Everything works perfectly except for my internet connection. When I talked to Tech Support (before they realized my warranty coverage had expired) they said the NIC card was most likely failing. Hence, the reason I bought the adapter after talking to Dell Parts and Upgrades. When I try to install the adapter, I always get the following error: Windows cannot load the device driver from this hardware. The driver may be corrupted or missing (Code 39). I called D-Link and worked with them for awhile. I tried the driver software that came with the device and downloaded the drivers directly from D-Link's site as well. I see the adapter in my device manager with a yellow exclamation point beside it. Every fix I've tried has failed. I am simply trying to set up a wired connection from my PC to my modem for internet. I have tried reworking the BIOS to ignore my built-in NIC and look at this device instead, but that didn't work either, so I'm back to ground zero. I don't understand why Dell can't provide the drivers if they sell me the part. Someone from an earlier posting said the drivers from the company should work. D-Link can't provide drivers that work, so what am I supposed to do? I've already replaced the initial device and have the same error. I would really appreciate any help you can offer.Could someone please help me?