http://en.community.dell.com/techcenter/enterprise-client/w/wiki/2065.dell-driver-cab-files-for-enterprise-client-os-deployment.aspx

extract using:

expand [-r] []
expand -d .cab [-f:]
expand .cab -f:

more info at: http://technet.microsoft.com/en-us/library/dd744339(v=ws.10).aspx