Trick Driver Question

[SteveMac]

I have a system of remote PCs that run a special build of Windows XP that each connects to two 'Eleven' arduinos.
This was built in 2012.

The problem I have is this. I need to replace some of the eleven's.
I can't get the same model of eleven.
The ones I used had a mini USB connector, not a micro USB connector.
The new ones need a different driver.
Adding a driver is a spectacularly big job.

Is there any way I can reprogram the device processor on the new eleven to make it appear to the PCs as an older eleven?
Will the older driver work with the newer hardware (if the new hardware is made to appear as the older hardware)?
Has anyone had to do this before?

TIA
SteveMac