I came across the Web site for Powerbook Guy, who offers many, many parts for old Powerbooks, as well as repair and upgrade services. He has Powerbook 1400 logic boards for $9.95 (used) to $19.95 (new), and when you think about it, getting a logic board only, or a processor card ($7.95 for a 117 MHZ, $9.95 for a 133 MHz) is easier than cheaper than buying a whole 1400 for spare parts. Most of that savings is due to shipping -- a whole Powerbook is freakin' heavy, and a single board weighs only a few ounces. He has a 48 MB memory card for the 1400 for $119 ... OUCH. I couldn't find a 48 MB card anywhere, but I did find a 32 MB card, and it only cost me about $10 over the Low End Mac swap list. So you've got to know what things are going for before you leap.
Powerbook Guy also has some great prices on used laptops: iBook G3s from $239.95 to $379.95, iBook G4s from $379.95 to $629.95.
Personally, I'm not comfortable playing more than $350 for any of these iBooks, but the fact that an iBook G4 can still fetch from $400 to $600 means that, if you can manage to find a buyer, getting rid of a 5 or more year old Mac laptop can really boost your bottom line. Of course, since an iBook G4 can run 10.3.9, 10.4.whatever and maybe even 10.5 with a RAM boost, th0se 'Books are not anywhere near obsolete.
Follow me now ... the iBook G4 1 GHz were sold, pretty much, during 2003 and 2004. Now it's 2007, so most of those have seen between three and four years of service. Now Apple is on OS X 10.4, and will release 10.5 in the spring. So even if you don't want to run 10.5 on the iBook, you can definitely run 10.4, and that will probably carry you comfortably for between three and five more years. So that iBook will have an easily usable life of between six and eight years before you have to start scrambling (and that scrambling is what This Old Mac is all about).
As I've said many times before, it all comes down to whether or not the apps you want to run will work with the hardware and operating system available. In keeping with that, Windows is much more forgiving; you can run the latest Firefox browser even if you have Windows 98. Not that you'd want to, but it can be done. With Mac, OS X is the dividing line -- all modern browsers run on X only, and not on OS 9 or anything before that.
For me, the Web is the critical app -- the nature of Web browsing is constantly changing, and if your hardware and software can't keep up, your computing experience really suffers. For me, the Powerbook 1400 is a niche machine. For writing and e-mail and basic Web browsing, it works. But will it show YouTube videos, streaming video from network TV sites, complicated Flash animation and work with things like Google Docs? No.
But these G4 notebooks will do these things, and as long as the browsers continue to work with the latest version of OS X you are able to run, you'll be in good shape. Things like Microsoft Office, even Photoshop, will always be available in versions suited to your hardware and OS. And hopefully e-mail protocals won't be radically changing, and today's e-mail clients will be able to handle the major providers' POP and IMAP servers for some time to come.
Still, the Web -- and the browsing thereof -- is the 900-pound gorilla when it comes to computer obsolescence, and you will know when the bell begins to toll.