When he says that the users have different ISPs and hardware, I think he is hinting at the bigger problem. The users will need local administrator rights to set up their home ISP connections. This means they will quickly learn how to disable or remove any nanny-type software.
Personally, I would do whatever it takes to keep from giving them local admin rights. The PCs will be spyware infested and bogged down with non-corp software very quickly. Even if your support policy is to reimage the laptop, you will see many people who do not report problems because they don't want to a re-image, and viruses will be transported inside the firewall on the laptops.
You might actually find it is easier to have them bring in their DSL modems and ISP setup disks.
One clever option I suggested to my bosses is that we supply the laptop, AND a LinkSys or DLink DSL/Cable router. The $50 router will be a gift to the users, and that's less than the cost of 1 house call. They will be on their own to get the router working with their ISP and will not have to modify anything on the laptop. (Most ISPs do provide support pages for these devices, or it is not too bad for you to make instructions for the brand of router you choose, and the various ISPs in your area.)
Now you load whatever nanny software you want, and the users will not be able to uninstall it. Of course nothing is 100% secure. They can always use a boot CD to crack the local admin account, or pop in a WinXP cd and rebuild it...
Now you'll see the next problem... Printer drivers for the oddball printers they have at home. :) The best idea I have here is to require the users to bring the printer in to work 1 day and configure it. It's a pain, but it's better than making housecalls or giving them admin. How often does someone get a new printer? Same could apply to external zip drives or PDAs. Have them bring them in to be installed.
Good luck. These are very tough problems, though.
