If your asking for the Windows CE 2.0 Ethernet Components folder files, you've answered your own question:They are already imbedded in the Z50. (The CD folder is for CE 2.0 machines, the Z50 is running CE2.11 which already includes the files.
Search the Windows directory and you should find:
arp.dll, dhcp.dll, ndis.dll, ne2000.dll already there.
You might be better off finding a PCMCIA ethernet card that is natively Windows CE compatible. (I've used a SOHOWARE card for years that was simply plug-n-play). [Around $25.00US]
3COM PCMCIA ethernet cards have historically been a problem with Windows CE.