It can be awkward to drop in on a client and then ask if you can use the machine's Remote Disc feature to wirelessly borrow the optical drive on one of the client's computers if he hands you material on a CD-ROM.
In several recent cases, hackers have infected hundreds of thousands of Web servers with software that performs "drive-by downloads" on any visitor's machine, installing password-stealing Trojans or turning the PC into a spam-spewing zombie.