you will NOT be banned unless valve breaks their own rules
im not sure if posting a link to steam website counts as external links but heres a quote from the steam website
The following will not trigger a VAC ban:
* Using chat programs like X-Fire
* Playing multi-player mods which do not modify core .EXE and .DLL files
* System hardware configurations
* Updated system drivers, such as video card drivers
* Using custom SKINS, sounds or maps
just dont edit exe or dll and ur alright (textures edit iwi)