Its pretty simple to play CS:Source on Ubuntu.
Assuming you have cedega and a fully updated css:
1- Go to css folder and do: chmod 777 * -R
2- Edit ~/.transgaming/config and add at the bottom
"Windows" = "win2k"
3- Run css with:
cedega hl2.exe -steam -game cstrike -console
The game runs very smoothly, although some objects and the menus fonts are messed up.
Hope it helps!
61.11 Nvidia drivers
gforce4 ti4200 128