Technology is great! I can be out of the office all day yet have access to my computer, calendar, contact information, Word & Excel documents, etc.
Just about all the big wireless carriers offer these Phone/PDA combos and prices on these devices are dropping all the time. I bought mine October 2002 for $550 and as of July 2003 it runs $399. These devices provide all the standard PDA features plus they allow you to surf the web, send/receive email, share documents, and much more.
With a PDA built into your mobile phone, you no longer have to carry two devices. It's more convenient to communicate with your contacts stored in one device - no more back and forth between devices.
There are also wireless modems on the market for your laptop that allow you to surf the web at speeds faster than an ISDN connection. Sprint makes a good one that I've worked with: www.sprintpcs.com – Shop Phones > "PCS Connection Cards".
Wireless carriers are always running promotions on these wireless products/services. You can often get the devices at a much lower cost if you sign a longer service agreement.