Does anyone have a portal/portal 2 texture pack?
Also, if someone can, how do you import the Portal 2 textures to Portal 1? (I've seen that a lot.)
Thanks
Technically all the textures from portal 2 are the same kind of format as the portal 1 textures, however they are a different version. You can convert them in bulk using VTFedit to change them to the newest .vtf version and then place them in the correct folder.
Is it actually necessary to convert them to the newest form? Ive used a couple of potral 1 textures without changing them and had no hassles with it. What does changing the vtf version do?
I think in terms of boolean variables. Generally, it makes things easier.
@Daschnookle:
Here you can find some textures packs:
http://www.tophattwaffle.com/?page_id=63
Most of them can be used on Portal2 as they have been developed for the Source engine (CS mostly). I have all "RealWorldTextures" working and "Water textures" too (a few of these don't work properly though).
useful tools and stuff here on TWP 
[spoiler]
[/spoiler]Well if you want portal 2 textures to portal 1 you will need to convert it as portal 1 cannot have the newer version of .vtf. I believe it is not compatible with it (notice the word believe).
You need to import the vtf into vtfedit and change the version to 7.2, unfortunately, you have to do all of them manually, unless someone already did it and uploaded it online.