Can't watch videos on Snow Leopard

Hi, I bought a new macbook 1 month ago.
It came with Snow Leopard and QuickTime X.

I have more computers (all with Windows). In my main computer I have a partition shared with loads of videos (some avis in DivX/Xvid, mpgs, mkvs, mov, etc).

From my macbook I see perfectly the mapped drive, but I am unable to see most of the videos.
I could see with QTX some videoclips (avis not in DivX and mpgs) but am absolutely unable to see the rest of the videos (divx, mkvs, mov, etc).
Each time I open it, it says that i dont have permissions for this action (??).
I have checked the permissions in my windows pc and all the files have the same permissions - I can access and watch without problems from 4 different computers, including my macbook with windows (I installed it in another partition using bootcamp).
I downloaded and installed perian 1.1.4. Same results.
I installed QT 7.6.3 (7.6.4 does not work in Snow, lol!) and the same result. I installed VLAN and the same!
If I try to copy the video to the macbook, when I open it QT7 says that it is not a valid file (not true, in windows I can see it...)

The "funniest" thing is that if I try to open a mov I downloaded from Apple webpage (star trek trailer in hd), it says the same xDD

I am a little bit frustrated for this... what else can I do?? Any help?
Thanks!

I have posted in another thread about this. There is quite a few problems out there with SL and QuickTime X

Only solution i came up with for the other thread was to download VLC which there is a download link on there home page.
You can watch just about any audio and video media formats known to man ATM.

Think  needs to address this is a coming update

Cheers

EDIT : Then again make sure your SL and QuickTime X has the latest updates too and try again. If not highly recommend VLC

My first suggestion would be to find out whether it's the network or something else on your computer that is the problem - try taking one of those files (the ones that aren't working right) and put it on a flash drive (do this on a computer that CAN read the files correctly), then attempt to play the video on the SL Mac. If you get the same error, then it's not a network problem, it's something else that is permissions based that is blocking you from using these files....

I've never gotten mkvs to play properly in Quicktime X, but I do watch them on QT7, VLC, and Plex on all of my macs that have SL.

Sorry, when I wrote "VLAN" y meant "VLC", my mistake.
I will try the usb in order to check if the problem is the network.
Thanks!