I've had mixed experiences with the WRT54G. In a home environment, they work spectacularly - except for the odd time now and then where the firmware locks up and they need to be reset (this only happens about twice a year for me, so it's not a big deal) - but they fail equally spectacularly in environments with more than, say, twenty users. They seem to have excellent range and they support AES encryption, which is both wonderfully simple and secure. They also have pretty standard antenna mounts, so if you're the kind of person that does hardware hacking like that, you could probably Yagi the thing so you can compute from the next county, if you really want.
In terms of reception on your machine, that depends both on your antenna location (the Powerbook has the unfortunate side effect of being encased by a Faraday cage), and the broadcasting strength of your wireless device. I've found the WRT54G to be perfectly acceptable in this regard and if it's not cutting the mustard in your situation there are more powerful antennae you can purchase for the unit that increase its transmit/recieve gain. I myself haven't had to use these, but as always your mileage may vary. The actual protocols themselves (802.11b and .11g) don't define the range. It's likely that older "b" models didn't have as powerful radio equipment, with falling prices on components it seems likely that newer "g" models simply have more powerful radios.
In terms of pure features-per-dollar however, I have to say I'm absolutely thrilled wth HotBrick (www.hotbrick.com
) firewall/routers. They're made of metal, are super-easy to work with via the Web interface, and their reception seems just top-notch. There's also just about every log and feature that you'd ever want to tweak (in either a home or business environment, which is really killer), and thery're somewhat smaller than the WRT54G units.
I would stay far, far away from any product that D-Link offers - I have never had a good experience with their products. Poor range, horrid reliability, and general overall shoddy build quality have led me far, far from the world of D-Link.
Just to add to the confusion, more and more companies are producing the "XTREME SPEED!" routers, which use a non-standardised radio broadcasting type called MIMO to achieve speeds faster than 802.11g, which is 54Mbit. In order to take advantage of these features, you need a wireless card that supports MIMO, which currently (to the best of my knowledge) no built-in cards, especially not the AirPort Express cards, do. In other words, you will need to purchase - and use - another, separate WLAN card if you want to use the "108 MBit" wireless devices. These cards are backwards-compatible, so if you want to go that route, go ahead - I always thought, though, that a Powerbook was all about the clean lines and having another card jutting out the side seems to ruin the aesthetic.
By far the simplest and cheapest route is to purchase a device that "just" does 802.11b/g signals, like the WRT54G or its ilk. I just have to say again, stay far, far, far away from D-Link unless you *like* headaches.
Hope this helps.