ExpressCards are the new PC Cards. They're thinner, lighter, and faster. The PC Card is alive and kicking--some new notebooks still include a PC Card slot, and some offer both PC Card and ExpressCard slots--but the format's days are numbered.

Last week I gave you the ExpressCard backstory--what it is and how it differs from PC Card technology.

This week I focus on what you can do if you have PC Cards but your new notebook has only an ExpressCard slot. Similarly, what options do you have if you want to use an ExpressCard device on a notebook that has only a PC Card slot? Read on.

Can I Use a PC Card in an ExpressCard Slot?

The PC Card and ExpressCard interfaces are not compatible. What's more, some new notebooks come with an ExpressCard slot in lieu of a PC Card slot.

The incompatibility between PC Card and ExpressCard technologies has been particularly noticeable to mobile professionals who bought new ExpressCard-only notebooks but couldn't find compatible cellular wireless modems to use with them. If you're in that situation, you may have some options. For instance, some cellular wireless modems are available as USB devices, and every current notebook has at least one USB port.

I've found a few commercially available options that let you use PC Card cellular modems on computers that lack a PC Card slot. In essence, these devices are external PC Card slots that attach to your notebook's USB port.

The USB Adapter for 32-bit CardBus Wireless Modem Cards ($180) is designed to let you use a supported PC Card cellular wireless modem via a computer's USB port. The PC Cards supported are in the CardBus format, which use a 32-bit bus instead of the slower 16-bit bus of older PC Cards.

Also, the USB Adapter for Select 16-bit 3G PCMCIA Cards ($140) lets you use older, 16-bit cellular wireless modem cards via a computer's USB port.

But what about using other PC Card devices if your new notebook lacks the right slot? Duel Systems is said to be developing a PC Card to ExpressCard adapter. As of this writing, the product had not been released but was expected to be available in February for about $119.

Can I Use an ExpressCard in a PC Card Slot?

Unfortunately, no. However, it's worth noting that most ExpressCard devices, such as wireless cellular modems, were first available as PC Card devices--so you should be able to find what you need in the older format.

ExpressCard modules that specifically take advantage of the ExpressCard's faster bus interface, such as Gigabit Ethernet devices, are generally not available as PC Card devices, because of the older technology's slower throughput. In such cases, you'd need to upgrade to a notebook with an ExpressCard slot to use those devices.

For more information about ExpressCards, go to the official Web site.

How About Notebooks With Both?

Some new notebooks have both PC Card and ExpressCard slots:

• Sony Vaio SZ series
• Lenovo ThinkPad T60 series
• Toshiba Qosimo G35
• Fujitsu LifeBook S7110