I have an older machine and when I try to run Steam for Linux, it won't even start. What's wrong?
The Steam for Linux client requires a processor that supports SSE2. If your processor does not support SSE2, the Steam client will not run. If you run the Steam client from the command-line, you will see an illegal instruction exception caused by the lack of SSE2 support.
In order to run Steam for Linux you will need to upgrade to a processor that supports SSE2.