We just got a batch of Optiplex 990's in and after creating a Windows 7 64 image and adding it WDS, we are unable to deploy the image thanks to missing nic drivers.
At this time I have injected 4 .inf files from 2 different Windows 7 NIC driver packages available from Dell, as well as 1 .inf file from a Vista 64 package. None have worked.
I found on an acronis discussion that some people had success after disabling Intel's MEBx on their 990's. Again, same results, still can't find proper drivers.
Finally, though probably not related to this issue, I have turned off RAID from the SATA options within the BIOS.
I am running WDS from Server 2008 Enterprise SP2 32 bit.
The NIC driver packages I used are Broadcom_57XX-Gigabit-Contro_A00_R292146.exeand Intel_825xx-Gigabit-Platform_A02_R313802.exe, which are available both from the Dell website as well as an included CD.