I'm trying to get my QuickCam Express usable for things like Skype and aMSN. I unplugged my webcam, used Synaptic to install 'qc-usb-source' and 'qc-usb-utils' (both version 0.6.6-5), then rebooted. When I tried plugging in my webcam, it would not be picked up by Skype or aMSN. I don't know what to do next. Any suggestions?

...help?

You need to run module-assistant to build and load your module. Just start it from a command line and run through the steps. When you get to "Select" you should see qc as a choice. Select it and carry on. When finished do an to confirm the module as been loaded ok. I don't recall if you need to stop and restart your x-server.
That should do it for you.
cheers,
jdk

When I select 'qc-usb' and select 'BUILD', it says "Build of the package qc-usb-source failed!" What should I do?

After selecting qc-usb did you go through the Search and Get steps before moving on to Build?
Cheers,
jdk

Yes, I did. No dice.

Is the qc-usb-source package installed? Also do you have the kernel headers installed? Does the failure give you any hint about what m-a is unhappy about? A little more information would be helpful here.
jdk

Yes, qc-usb-source is installed; I even reinstalled it. I don't know what kernel headers are. The log file has a bunch of 'Error 2's at the end. Funnily enough, it looks like the same errors I get every time I try to compile a tarball.

what is the result of executing this?
cheers,
jdk

It does nothing for a few seconds, then it says this:
v linux-headers -
v linux-headers-2.6 -
p linux-headers-2.6.25-2-386 - Linux kernel headers for version 2.6.25 on i386
i linux-headers-2.6.27-11 - Header files related to Linux kernel version 2.6.27
i linux-headers-2.6.27-11-generic - Linux kernel headers for version 2.6.27 on x86/x86_64
p linux-headers-2.6.27-11-server - Linux kernel headers for version 2.6.27 on x86/x86_64
p linux-headers-2.6.27-3-rt - Linux kernel headers for version 2.6.27 on Ingo Molnar's full real time preemption patch (2.6.26.5-r
idA linux-headers-2.6.27-7 - Header files related to Linux kernel version 2.6.27
idA linux-headers-2.6.27-7-generic - Linux kernel headers for version 2.6.27 on x86/x86_64
p linux-headers-2.6.27-7-server - Linux kernel headers for version 2.6.27 on x86/x86_64
idA linux-headers-2.6.27-9 - Header files related to Linux kernel version 2.6.27
idA linux-headers-2.6.27-9-generic - Linux kernel headers for version 2.6.27 on x86/x86_64
p linux-headers-2.6.27-9-server - Linux kernel headers for version 2.6.27 on x86/x86_64
p linux-headers-386 - Linux kernel headers on 386
i linux-headers-generic - Generic Linux kernel headers
v linux-headers-lbm -
v linux-headers-lbm-2.6 -
p linux-headers-lbm-2.6.27-11-generic - Header files related to linux-backports-modules version 2.6.27
p linux-headers-lbm-2.6.27-11-server - Header files related to linux-backports-modules version 2.6.27
p linux-headers-lbm-2.6.27-7-generic - Header files related to linux-backports-modules version 2.6.27
p linux-headers-lbm-2.6.27-7-server - Header files related to linux-backports-modules version 2.6.27
p linux-headers-lbm-2.6.27-9-generic - Header files related to linux-backports-modules version 2.6.27
p linux-headers-lbm-2.6.27-9-server - Header files related to linux-backports-modules version 2.6.27
p linux-headers-rt - Rt Linux kernel headers
p linux-headers-server - Linux kernel headers on Server Equipment.
p linux-headers-virtual - Linux kernel headers for virtual machines

and what is the output of jdk

Linux jump-desktop 2.6.27-11-generic #1 SMP Thu Jan 29 19:24:39 UTC 2009 i686 GNU/Linux

You do seem to have the correct headers installed. Do you have gcc installed by any chance? I ask this because you said, Maybe you should post the errors you get when you try to build the module.
Cheers,
jdk

Yes, I have gcc installed.
The last few parts of the build logfile:

make[3]: Entering directory `/usr/src/linux-headers-2.6.27-11-generic'
CC [M] /usr/src/modules/qc-usb/qc-driver.o
/usr/src/modules/qc-usb/qc-driver.c: In function ‘qc_i2c_init’: ▒
/usr/src/modules/qc-usb/qc-driver.c:827: warning: assignment from incompatible pointer type
/usr/src/modules/qc-usb/qc-driver.c: In function ‘qc_isoc_start’:
/usr/src/modules/qc-usb/qc-driver.c:1869: warning: assignment from incompatible pointer type
/usr/src/modules/qc-usb/qc-driver.c: In function ‘qc_v4l_ioctl’:
/usr/src/modules/qc-usb/qc-driver.c:2531: error: ‘struct video_device’ has no member named ‘type’
/usr/src/modules/qc-usb/qc-driver.c: At top level:
/usr/src/modules/qc-usb/qc-driver.c:3010: error: unknown field ‘type’ specified in initializer
make[4]: *** [/usr/src/modules/qc-usb/qc-driver.o] Error 1
make[3]: *** [_module_/usr/src/modules/qc-usb] Error 2
make[3]: Leaving directory `/usr/src/linux-headers-2.6.27-11-generic'
make[2]: *** [default] Error 2
make[2]: Leaving directory `/usr/src/modules/qc-usb'
make[1]: *** [binary-modules] Error 2
make[1]: Leaving directory `/usr/src/modules/qc-usb'
make: *** [kdist_build] Error 2
^Y