> I used a Powerbook (Lombard, not G4 model) during 3 months during a stint > overseas and frankly, unless you are absolutely anal-retentive about exact > color hues and the such (let's face it, total control on the web is an > absolute oxymoron) it will do the job for you. If budget allows, you might > want to compliment your laptop with an independent displayThis is how I worked (as a Senior Interface Developer for an ebiz-web-app-consulting-custom-solutions-b2c-b2b company) for a couple of years. Having a Powerbook with a monitor attached to it makes for lots of extra desktop space which is vital for apps like Dreamweaver (which I actually don't use) and Adobe Illustrator.
Having a CRT and an LCD to view the site on allows me to make sure the site is looking good under both environments and being able to change the bit depth on each display, independently, allows me to catch most/all display environments.
Add in VirtualPC, and I can test multiple PC environments because I can set up as many virtual PC's as I want and install whatever OS's are important to me (based on the project in hand and the environment the end user will be in).
Just do yourself a favor and get the fastest Powerbook you can afford, and load up on the RAM. I've got a tiBook (550mhz with a half gig of ram) and it's still too slow (but when have you ever had a machine that was fast enough?).