Saving iMovie 4 projects on an external hard drive

Question

I'm starting the ambitious project of copying our family videos from 8mm tapes to iMovie to eventually making DVDs. since I don't have much disk space on my iBook, my plan is to put the iMovie files on an external hard drive & work from there. Here are the system specs:
Camera: Sony DCR-TRV520 (Digital 8)
Computer: iBook 800 MHz PowerPC G3, 28GB hard drive, 5GB available
OS 10.3.9
iMovie 4
Hard Drive: LaCie Eternet Disk mini 300GB (150GB available) format: Mac OS Extended
Problem: Open a new iMovie project on the external hard drive. Start to import the footage. After one or 2 seconds, the image freezes and import aborts.
Solution: Open a new project on the computer. Footage imports fine.
Problem: Can only import 1/2 hour or so of video before I'm in trouble. Files WAY too big for my itty bitty iBook!
Solution: Make a new iMovie file on the external hard drive & copy the clips from the computer to the hard drive. (this takes TONS of time!)
Problem: Open movie file on the LaCie. Import the clips. Clips show up but won't play!
Question: Is there any better way to do this? Why won't the project work on the external hard drive?
I teach video production at a high school and have done this many times on newer iMacs (iLife 6). We can't save every project on the computers, so certain projects I'll copy to an external hard drive. I've never had a problem working on an iMovie project from the hard drive. I considered uploading my movies on the computers at school, however then I'm stuck with iMovie 6 files on the hard drive and iMovie 4 at home.
Any suggestions -- other than get a newer computer?

Answer 1

Importing new footage from a video camera and working with iMovie with footage already on the computer are two completely different things.
At school, do you actually IMPORT video from digital camcorders directly to the USB drive as you said you were doing at home?
Because while you can indeed work on iMovie projects off a USB drive if you are not actually importing video, the whole importing process from a Firewire camcorder is sort of a streaming video type transfer and Firewire is used because it has a mode for this type of transfer. USB, on the other hand, can not import video from a camcorder straight to a USB drive reliably because there is way too much CPU overhead associated with USB transfers and it therefore can not keep up with the "streaming" video coming out of the camcorder.
If you want to find out more details, do a search for "isochronous" with Firewire. Firewire uses type types of transfers. Asynchronous transfer which is like USB uses where you transfer data, wait for the CPU to respond, then transfer the next chunk of data. Video transfer uses and isochronous process where, to put it very simply, the camcorder starts spitting out chunks of footage with a checksum and the receiving end receives it, calculates a checksum and if the checksums match, stores the chunk of data. If they don't match, the data is discarded and it starts to receive the next chunk of data. There is no ability to resend failed data so you get dropped frames in your footage.
If you import via Firewire from Camcorder to Mac then directly to an external USB drive, the transfer from Mac to USB drive will be too slow as the CPU and drive have to start doing their "did you get it?", "Ya I got it, send another/No, send again please", "OK here it comes" routine while in the meantime the camcorder to Mac Firewire transfer is just pumping out data at a fixed rate. Once the USB connection falls behind the process aborts.
Patrick