Ok, so I booted the livecd, copied the contents of /lib/modules/3.0.2+/kernel/sound across (via tar archive) to a usb key and booted up the hard disc install.
I looked in /lib/modules/3.0.2+/kernel/sound on the HDD install and it's non-existent, which is odd but expected. I untarred the archive in there, being careful to make sure I kept permissions/folder structure correct. All good, so I run "update-modules" and tried /etc/rc.d/alsasound start, which gave me no dice.
Scratching my head a little, I tried modprobe soundcore, which responded with that it didn't know where soundcore was. This was odd, as I definitely ran update-modules and put it in the right place. I could insmod soundcore if I gave it the specific location, so I know that at least it's compatible. I also tried alsaconf but it came back as no cards. I'd like to point out that under OSS or using the LiveCD, my soundcard gets detected just fine.
Now here's the really odd part, when I had rebooted, the folder in /lib/modules/3.0.2+/kernel/sound had disappeared! Is /lib/modules/3.0.2+ being created on boot or copied from a filesystem image somewhere?