Hardware scan/inventory application for corporate network?

I'm looking for some sort of free application that can create an inventory of a PC's hardware and store it in a log file on a network drive. It needs to be able to run without user interaction and without administrator priviliges. Specifically, I want to run it from a network share using my domain login script, and I want to have it save the results back to the same network share.

The issue I have is we have a hundred or so PCs scattered between desktops at our office and people with laptops on the road. The existing inventory we have of all systems is out of date, so we are trying to update it. Everyone logs on to our domain, so I think this will be the easiest way to distribute the program without having to manually go to each PC.

Really all I need to know is the BIOS serial # (Dell service tag #, since they're all Dells), the logged on user, and the computer's netbios name. We just want a picture of what PCs are being used by what people, and which of the several hundred PCs in the inventory spreadsheet are even still being used.