First, some output.

pxc@cooldude:~$ sudo apt-get install --reinstall kate
Reading package lists... Done
Building dependency tree
Reading state information... Done
Reinstallation of kate is not possible, it cannot be downloaded.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

pxc@cooldude:~$ cat /etc/apt/sources.list
# deb cdrom:[Kubuntu 7.10 _Gutsy Gibbon_ - Release amd64 (20071016.1)]/
gutsy main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

deb http://us.archive.ubuntu.com/ubuntu/ gutsy main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://us.archive.ubuntu.com/ubuntu/ gutsy-updates main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## universe WILL NOT receive any review or updates from the Ubuntu security
## team.
deb http://us.archive.ubuntu.com/ubuntu/ gutsy universe
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy universe
deb http://us.archive.ubuntu.com/ubuntu/ gutsy-updates universe
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://us.archive.ubuntu.com/ubuntu/ gutsy multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy multiverse
deb http://us.archive.ubuntu.com/ubuntu/ gutsy-updates multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy-updates multiverse

## Uncomment the following two lines to add software from the 'backports'
## repository.
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://us.archive.ubuntu.com/ubuntu/ gutsy-backports main restricted
universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy-backports main restricted
universe multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository. This software is not part of Ubuntu, but is
## offered by Canonical and the respective vendors as a service to Ubuntu
## users.
deb http://archive.canonical.com/ubuntu gutsy partner
deb-src http://archive.canonical.com/ubuntu gutsy partner

deb http://security.ubuntu.com/ubuntu gutsy-security main restricted
deb-src http://security.ubuntu.com/ubuntu gutsy-security main restricted
deb http://security.ubuntu.com/ubuntu gutsy-security universe
deb-src http://security.ubuntu.com/ubuntu gutsy-security universe
deb http://security.ubuntu.com/ubuntu gutsy-security multiverse
deb-src http://security.ubuntu.com/ubuntu gutsy-security multiverse

#Virtualbox stuff
deb http://www.virtualbox.org/debian gutsy non-free

#KDE 4!
deb http://us.archive.ubuntu.com/ubuntu/ gutsy-proposed restricted main
multiverse universe
# deb http://ppa.launchpad.net/kubuntu-members-kde4/ubuntu gutsy main

The problem, if it's not already clear, is that the package manager wants to
download some packages from a repository I have (intentionally) removed. I
need to be able to search through my packages for any containing "ppa" in
the package version, and replace them with an older one. How can I do this?
(How can I make Kubuntu stop thinking that those packages are to be
downloaded from the ppa repository!?)
-- 
Amarok: Rediscover your music.
-- http://amarok.kde.org

Sabayon Linux: Cutting Gentoo's edge.
-- http://www.sabayonlinux.org