What have you done / what is broken and how.
Clarifying questions:
* What major version are you on / what update are you on (shouldn't be super relevant here, but it's a good habit to get into).
* What drivers did you add & how?
* What is broken exactly / what errors are you seeing?
If you've added a duff driver to the WinPE image(s) that should only affect boxes that require THAT driver. Say it's a 3COM driver, it shouldn't affect devices with INTEL NIC's for example.
So I'm more than a bit confused how it is / what you've to "break PXE booting in general" ... more information would be needed here.