Does anyone have one and are they any good? The one I am possibly being offered has USB - does anyone know if it's possible to get a USB key to work in them?

I think that the 3400c's are good Powerbooks. A USB key would surely work in Mac OS 8.6 or above.

Damn, I wanted to put 7.6 on it.

Dual boot!
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iMac G5, Powerbook G3/333, Beige G3MT, PM 6200CD, RS/6000

How would you do that? With partitions? I was going to say there probably wouldn't be enough disk space, but I'm forgetting how tiny the system was back then!

Dual partitions is one way, or one partition and an OS switcher. I can't remember the name of the switcher program, but you can happily fir 7.6.1 in 200-300MB, and laptop hard drives are so easy to come by, and under 10GB they cost next to nothing!
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iMac G5, Powerbook G3/333, Beige G3MT, PM 6200CD, RS/6000

Yep, just make two partitions and put a system folder on each. OS 9 will fit in a couple of hundred MB or so (possibly less, I can't remember exactly), 7.6 in about 25 MB, both assuming you install only the system components needed for your Mac as opposed to a universal system with tons of extensions you don't need, and (in the case of 7.6) 68k code. Note that 7.6 actually has a bug in the installer - don't select Cusom Install as that in fact installs a Universal system - Easy Install will install a system just for that Mac, and you then have to go through it and manually delete the bits that you don't want, to save space.

Would the USB in fact work in 8.1, given that the first iMacs shipped with 8.1 and they had USB?
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Main system: custom C2D 2.66GHz tower/4GB RAM/2600XT 512 MB/500GB HD/XP Pro x86+Vista Business x64
Main Mac: Beige G3 minitower (Sonnet G4 500MHz/640 MB DVD/USB/Radeon 32 MB/OS 9.2.2+10.4.11)

On most USB key I see, it says Mac OS 8.6 or later. It may work in 8.1, but didn't the iMac use a special 8.1?

Ah yes, now you mention it I think it did, or it at least had some Enabler or something. Not sure if the special-ness is related to USB or not, but it could well be.
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Main system: custom C2D 2.66GHz tower/4GB RAM/2600XT 512 MB/500GB HD/XP Pro x86+Vista Business x64
Main Mac: Beige G3 minitower (Sonnet G4 500MHz/640 MB DVD/USB/Radeon 32 MB/OS 9.2.2+10.4.11)

They are a great machine...i almost got a 3400/200 once...but i think everyone knows about that...."The One That Got Away".

Anyway, you can dual boot one with 7.6.1 and other newer versions of the Mac OS...i have my 1400 set up in such a way. Just remember to give System 7 a big enough partition, as it is unable to read HFS+ volumes.

Also, the original iMac had a special copy of OS 8.1, which was especially made for the iMac.
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"I mean, how hard can it be?" - Jeremy Clarkson

The Infamous LCGuy - Now back with Amazing Working iMac Action™!

Just realised I don't actually own 8.6, so I'll have to install 9 just to use USB. Bummer. Better check it has enough hard disk space to handle both.

I know you mentioned that you would have to use OS 9 for USB, but if you ever get 8.6 running, here is a link that should give you full USB mass storage device driver support under 8.6

http://docs.info.apple.com/article.html?artnum=60394

I'm finding lots of links where people say flash drive support is available with special drivers for NT 4/OS 8 but I can't find links. There is one 32MB stick that has drivers for NT 3.5.1 and 7.6.1, but that forum post was so old that no responses would load as to what brand the stick was.

In case you have a Fantom brand USB drive -- here is the OS 8.1 download.

http://downloads.zdnet.co.uk/0,1000000375,39047032s,00.htm

The 3400c is actually a PCI-based machine (which is why USB support exists), so perhaps one of the mods can move this to the correct sub-forum?

Good point! Done.
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Power to the PowerPC!

I was gonna get a 3400...
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PPC Macs:

• Power Macintosh G4
  
• B&W Power Macintosh G4
  
• Power Macintosh 6500/225

As was i, as was i. But i guess we all know how that ended up.....
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"I mean, how hard can it be?" - Jeremy Clarkson

The Infamous LCGuy - Now back with Amazing Working iMac Action™!

I didn't end up getting it, but I got a G3 powerbook instead, with a good battery. Yay. Seemed to be a very good price too.

put 7.6.1 on a compact flash card in a pcmcia sleeve! now that'll be some fast bootin' action