Team Fortress 2 weird display glitch/problem (Pics)

I just got a new computer, its my first pc in a while (6-8years) so i don't want to start messing with stuff and f something up

i5 2500k 3.8ghz
8gb ram
Two HD 6870 xfire
1tb hd

StarWars TOR looks great and plays perfectly on the highest settings
Battlefield 3 I have on 'High' and runs perfectly (I was going to try Ultra but i was already blown away by high)
Portal 1 came with the system and it ran pretty much fine except for a tiny blocky glitch on straight lines when i turned side to side fast

- now, i just download TF2 from steam and everything looks fine .. the menus, options, the movie things, every box, window, text, etc.. is fine
but when I enter an online match or single player training I get a really weird spazzy crazy glitch with the graphics. if i stand still nothin happens but as soon as i move everything goes nuts, im seeing thru walls, floors, people and huge block and shapes are glitching out all over the place. its completely un-playable.
- the 'reccomended settings' were what i had first (everything on high), then i tried adjusting the settings and it didnt change anything.

- here are some pictures ::










i tried to take the screen shots without moving too much to show you how it completely spazzes out whenever i move just a tiny bit. you can see everything looks fine except for the environment. and in the online match the other character models and gun models were perfect, but the walls/floors/ceiling/ground/etc...etc... is all messed up.

Anyone have any advice or a solution? I really want to play this game, i love FPS and have heard and seen a lot of great stuff about it. thankyou