Initially, on the DC7800 SFF, I used the Intel kext, with reasonable
results (Lion).
Subsequently, I switched to MultiBeast, and this offered AppleIntelE1000
as a plug-in.
Its full path name is:
/System/Library/Extensions/IONetworkingFamily.kext/Contents/PlugIns/AppleIntelE1000e.kext
I have been using AppleIntelE1000e on DC7800 (Lion) and on DC7900 (Lion
and Montain Lion).
My early Mountain Lion installations were completed before tonymacx86 had
released MultiBeast For Mountain Lion, while tonymacx86 was still in his
apparently self-imposed embargo on Mountain Lion topics.
I suspect that I actually used MultiBeast For Lion to implement this
pre-release (but "Golden Master") Mountain Lion installation, or. much
more likely, a combination of iHackintosh and MultiBeast for Lion.
In any case, it was fortuitous that MultiBeast began to support
AppleIntelE1000e.