Windows XP setting encription for wireless network in HEX

I just purchased a used Dell 4150 laptop. It seems to function as expected. I have successfully tested the wireless feature without encription, so I know the laptop works.
My Actiontec wireless modem is setup with four sets of 26 hex characters in the encription.
The laptop has a place to enter the four fields one at a time. I have not been able to enter them successfully.

It has the usuall Wireless Network Connection Properties tab
In order to enter the encription, I have to check "Use Windows to configure my wireless network settings" which I've never used before because all my other wireless setups had very usable wizards.
I select my SSID and click Properties.
Wireless network key:
Network Authentication: Open
Data Encription: WEP

Network key (How to enter and keep it entered is my problem)
Confirm network key (How to enter and keep it entered is my problem)

key index scrolls 1 to 4.

So I need to enter each Hex key one at a time and make them stick.

That is what I apparently do not understand how to do.

Thanks in advance for all help.

Because this older laptop system only offers WEP.
Because WEP is in place on the rest of the units in the wireless network.

We opted not to use the pass phrase option in WEP which is translated into HEX. We tried pass phrases in WEP and kept forgetting the current pass phrase.

I guess we have not updated to WPA and am not familiar with it.