2wire 802.11g wireless adapters serial number and encryption key numbers does not match. There for I am unable to complete installation.

The Short Answer:
Your password might not meet criteria. It also depends on whether you use a custom encryption key. If so, then you either need to create a 10-digit or 26-digit hexadecimal number (numbers 0-9 & letters a-f) depending on whether you use 64 or 128-bit encryption.

The Long Answer:
A WPA password must be between 8-63 characters long, and must only contain ASCII printable characters.
The 2Wire User Guide for the 2700 states the following:
"You can customize the following wireless settings in the Wireless Security panel.
1. From the Authentication pull-down menu, select an authentication setting: WEP-Open, WEP-Shared, or WPA-PSK.
Note: WPA-PSK authentication is supported only on HG model gateways.
Open authentication allows users to configure their wireless adapter as either Open or Shared; in either case an encryption key is required. Shared authentication allows users to configure their wireless adapter for Shared authentication, which requires an encryption key. WPA-PSK requires that users configure their wireless adapter using TKIP.
2. To use the encryption key that came with your gateway, click the Use default encryption key radio button.
To create a custom encryption key, click the Use custom encryption key radio button. If you select Use custom encryption key, you can define a 64-bit or 128-bit encryption key. For 64-bit encryption, enter a 10-digit hexadecimal number. For 128-bit encryption, enter a 26-digit hexadecimal number. A hexadecimal number uses the characters 0-9, a-f, or A-F.
3. Click SAVE"

go to on screen "setup"
select "network"
select "Network easy setting"
Select "wireless"
do the connection check
the 2wire modem should be detected by the DY WL10
Select the 2wire
select "open system"
select WEP encryption
enter the encryption key, or just "key" (it is the number in brackets somewhere on the 2wire). Do not enter the brackets.
follow further prompts. It is easy from here on (famous last words)

the serial number of the 2wire is in the barcode and the wep key is the number below 10 numbers enclose with a bracket

I had to reinstall my 802.11b legacy 2wireless adapter. installation went fine until I had to enter the sn and wireless encryption key off of unit. These numbers are on wireless unit but have letters. The software won't accept what is written on unit. What do I do?

try getting the drivers from

http://support.2wire.com/index.php?page=download

I used this one:

Introduction
============
This document describes the procedure to install driver for the 2Wire Wireless USB Adapter under Microsoft Windows, and to run a wireless configuration program to configure your 2Wire Wireless USB Adapter to work with a 2Wire HomePortal or OfficePortal wireless gateway. These drivers work under Microsoft Windows 98SE, ME, 2000, and XP.

STEP 1 - Driver Installation
============================
1. Make sure your 2Wire Wireless USB Adapter has not been connected to your computer USB port.
2. Double-click on the file to run WinZip Self-Extractor. The driver installation files will be placed in your hard disk in the C:\TWWUSB_TEMP directory
3. Connect your 2Wire Wireless USB Adapter to an available USB port in your computer. Windows Found New Hardware Wizard will startup.
4. Select the option to search for driver in specific location. Specify C:\TWWGUSB_TEMP as the location of driver.
5. Follow on-screen instruction to finish driver installation.

STEP 2 - Wireless Configuration
===============================
1. Run the program WirelessCfg.exe in the directory C:\TWWGUSB_TEMP. You can do so by clicking on the Windows Start button and select Run. The Windows Start button is typically at the lower left corner of the screen. Type in C:\TWWGUSB_TEMP\WirelessCfg.exe to launch the program.
2. Follow on-screen instruction to configure your wireless setting. Enter the serial number and encryption key as they are printed on the bottom of your 2Wire wireless gateway.

I think you're getting confused.

You don't need to give the device serial number to a router. If you're using WEP it's going to be wanting one of two things. A key or the MAC address. The MAC address will be printed on the device in the format xx:xx:xx:xx:xx with a series of letters and numbers. If it's looking for a key, that is the security code set up by your router. Either retrieve that by using a wired connection to your router and accessing it directly, or use the hardware reset button on the back of your router which will wipe out the encryption settings. Either way, it will not accept the serial number because that's not what it's asking for.

what's your ISP name? for list of activation keys or keycodes go to:
http://www.2wire.com/?p=268
as for the serial nos. well every product has its own unique serial no. and you can't change that; it's every product's unique identity.

you cant change the wep key on the upstairs pc unless you change it on the 2wire 1st. the pc wep key has to match whatever the 2wire has it set to. go to the 2wire router settings throught the downstairs pc that is working to be able to see what the wep key is set to, then when you get the key or set a new one enter that key into the upstairs pc.

I have installed 2 2wire adapters with no problem. When using config software utility, don't select gateway (if using only adapter), then continue until sets up. No serial # required unless using a gateway, which is not needed to connect to wireless.