I have a set-up with two PCs running Windows XP, both acquiring data from external sources and saving it locally with time-stamp per sample.

At the end of each day I move that day's from both PCs to a third PC, where I perform analysis that depends on the saved timestamps to synchronize the signals acquired on both machines.

At the beginning of every day there is some synchronization signal to both PCs that helps me find out whether there's a clock difference between them at the beginning of the day, and I compensate for that difference in my analysis.

Everything went very well until I recently replaced one of the two PCs in the set-up to a newer one (the old one died). From that moment on, the difference between the clocks grows fast from the synchronization point and my analysis screws up.

The PCs can't be connected to the internet, but I can connect them both together through a Switch/Hub. Also, I can't give the synchronization signal more than once at the beginning of that day.

I wondered if there's any setting or software that can help me increase the time synchronization between the two PCs.

Many thanks.