IT'S ALIVE! IT'S ALIIIIIIIIIIIIIIIVE!
Woohoo! I got the my webcam working. So I guess I'll be answering my own question
(thanks to the ppl who read my earlier post anyway). As I said, I'm still a complete newbie at linux, so I ended up doing a LOT of fumbling around with little understanding. Still, in case it helps other newbies, I'll record here how to get a Logitech Quickcam Pro 4000 working on Debian (sarge), kernel 2.6.x (I'm running 2.6.8). (Some of this stuff will probably be blindingly obvious to experienced linux users.)
Please note: I AM a newbie, so a lot of this information may be wrong. Hopefully some linux guru will correct me in later posts, so read the entire thread.
Firstly, googling how to install this webcam under debian will turn up a lot of outdated information. I'll expain: There were previously two debian drivers for this (and a few related Logitech) webcam - pwc and pwcx (stands for Phillips Web Cam). Due to some controversial decisions, the pwcx was discontinued and excluded from the Debian kernel (you can still download the drivers from the original site - smcc.demon.nl/webcam/ , but they are no longer updated and have little documentation ) . Pwc is the main driver for the webcam, pwcx does the signal decompression so that the image looks right. Can't remember if this is exactly what happened, but if you plug in your Logitech camera, then run xawtv (which you can install with synaptic) and you just get a green image, you need the pwcx driver.
Luckily, some kind soul made another version, combining the code for pwcx into a new pwc driver. Get it at saillard.org/linux/pwc/ . As far as I can tell, it does not work on kernels less than 2.6.x, so may need to upgrade. A really easy way to upgrade is just to install the desired kernel image with synaptic (my thanks to a certain "bob2" on the debian IRC channel who told me that). Note - there is a standard pwc driver that comes with the 2.6.8 kernel, but if you don't install the saillard.org drivers, you just get a black image on xawtv.
I found installing the pwc driver very tricky as a newbie. There are two versions of it, you can install it as a patch (incorporated into the kernel itself, requiring you to recompile your kernel) or as a module (doesn't get compiled into the kernel, is activated after the kernel boots). Being a former windows id-jit, i thought patching it would be easier ("A patch! Cool! Just run the .exe and the let 'er rip!") so that's what I chose. Newbie beware! There's good instructions for how to install the patch on the saillard.org site, but what it doesn't say is that any time you recompile a kernel you have to configure it (at the "make menuconfig" step). There are hundreds of very technical options to tweak the new kernel, choose the wrong ones and your system may not boot at all (ahhh, memories - I've now reinstalled Debian 12+ times 8| ) so i'd recommend using the module pwc instead. If you do choose to patch your kernel, you need to install ncurses-dev (install with synaptic) to run menuconfig (ncurses is the code to draw up colorful menus in the terminal window). I think I got lucky configuring my kernel, for the most part, I used the default settings so far it's been ok.
To be extra safe, make sure that when you recompile your kernel, you keep at least one other working kernel on your system. That way, if it all goes wonky you can just pick the old kernel at startup. (In order to do this, I had mess around with /boot/grub/menu.lst file, (GRUB is the startup menu where you choose which kernel to boot with) I'm not confident enough to explain all the steps involved here, there's lots of recompiling howto's on google).
hope this helps...
