On Windows there are a slew of file recovery tools which will peer intently at an optical disc, retrying until they recover every possible file. The leading tool is probably Isobuster, but there are dozens of candidates for the title. There are few automated (or even user-friendly) data recovery tools on Linux or UNIX(tm) platforms, but common tools which are often even included with the core system or which are installable through the official package system are often sufficient for performing this critical task.
Ubuntu Gutsy is the first version of Ubuntu to include LTSP verison 5, MueKow. This new version of LTSP is designed to better be integrated with your distribution of choice, and while LTSP.org provides a source distribution, this is not recommended unless you are rolling your own Linux (e.g. "Linux From Scratch".)
There are oodles of guides to netbooting the ubuntu install. This is the story of what worked for me. You could start with any of the nearly-identical guides – I began with FRIS's "Install Ubuntu Gutsy over network or from a hard-disk" on Linux Mini. Now that we've gotten credit out of the way, here are the basic steps in broad strokes:
My Compaq nw9440 laptop has a Conexant HSF soft modem. To make a long story short, the only way to get it to work on Linux (that I know of, anyway) is to use the commercial Linuxant drivers. Conexant paid them to sell drivers, and they're twenty bucks. It's not a bad deal compared to 3com, which does not and may never have Linux support for Winmodems (especially older ones.)
UPDATE 200802120955 PST: On my system (Ubuntu gutsy, wine-0.9.47) this seems to be working. I will leave this page up for posterity. --drink
Since about 0.9.13 or so Wine has been capable of running Steam and its attendant games, which includes items like Half-Life 2. However, steam backups don't seem to want to work properly.