As I keep forgetting where the Dell driver cabs are, I thought that I should document it somewhere.... ;-)
http://en.community.dell.com/techcenter/enterprise-client/w/wiki/2065.dell-driver-cab-files-for-enterprise-client-os-deployment.aspx
For those of you out there that download drivers by going through the Dell support website, you'll find these CABs a dream. All the drivers for your model in one place. I generally just do an inf search through the folder structure, looking for the Device ID I need.