Hi coopern,
I will be glad to help you. Windows XP comes with native drivers for Dell USB keyboard and Dell USB mouse. Request you to let me know which windows XP service pack the computer has.
To check the service pack, request you to follow the below steps:
(1) Right click on my computer.
(2) Select properties and check under system information.
If the computer has any service packs less than service pack 3, then I request you to use the below link and upgrade it:
Do reply with your test results.