0xc000000d Win 7 x86 wim

[NiKiZe]

Just to confirm, Is this a efi-capable machine running legacy with 3Gb of ram or more, trying to boot win 7 x86 based winpe?

You are trying to use wimboot 1.0.6 ?
Yes then the fix is to use the latest wimboot, or maybe remove so you only have 2GB of ram, or not use win 7 based PE (windows 8 based pe can be used to install windows 7 for example)

Have you tried chaining directly to ipxe, without using PXELINUX at all?
If you can't change from using pxelinux in your pxe setup, maybe you can test with an ipxe.usb image?