QI'm interested in an IBM ThinkPad T41, T42 or X40, but none of these laptops includes a FireWire port. Is it possible to switch out the parallel port for a FireWire connector?

ANo -- you can't convert a parallel port into a FireWire port, or any other kind. You can, however, buy a PC Card adapter that will add one or two FireWire ports; this slim module plugs into a slot on the side of the laptop and sells for $30 and up.

(PC Cards are also sometimes called "PCMCIA Cards" and "CardBus cards"; likewise, FireWire also goes by "1394" and "i.Link" -- the industry somehow thinks using different names for the same product will build brand identities instead of just perplexing customers.)

Anyway: Why spend extra on FireWire? Many digital camcorders require it, and it's handy for devices such as iPods and external hard drives. A parallel port is usually needed only for pre-1999 printers and scanners.

My home network consists of a router and two laptops. Do I need to put a firewall on each computer?

The router should include its own hardware firewall, but each laptop also needs firewall software. Without that extra layer of defense, either laptop could pick up a worm outside your house, then spread it to the other computer once you return to the home network.

Many otherwise protected offices get taken down in this way: An employee takes a work laptop home, gets that infected, then plugs it back into the office.

-- Rob Pegoraro

Rob Pegoraro attempts to untangle computing conundrums and errant electronics each week. Send questions to The Washington Post, 1150 15th St. NW, Washington, D.C. 20071 or rob@twp.com.