as most of you all know in order for textures etc to work properly you need to change Binvalidateolderfiles from 0 to 1.
but when i go to save (im using notepad like the readmes etc.) it says cannot create the c;/program files/bethesda softworks/fallout3/fallout_default.ini file.
make sure the path and file name are correct.
I have vista if thats whats confilcting it..

Vista is indeed what's conflicting here. The problem here lies in administrative rights and even if you have them, User Account Control (UAC in short) will also prevent you from doing it.
So what you want to do is edit fallout_default.ini as you'd normally do in notepad. Change the value of Binvalidateolderfiles to 1 and go to File>Save as...
Then save it on your desktop as fallout_default.ini and as type, choose all files (so the extension will become .ini)

Now, just cut/copy fallout_default.ini from your desktop and paste it in C:\Program Files\Bethesda Softworks\Fallout 3
It will pop up with a question from UAC if you want to continue, just click continue and yes all times asked. Then replace and overwrite the old file.

It will work now

seems a bit cumbersome, can't you just save and keep the current .ini format? I mean then you can just save and overwrite right away!

your a genius it worked.
but the textures still dont appear right,
ive got the shape of the objects just not the color etc.

quote Tyhon

seems a bit cumbersome, can't you just save and keep the current .ini format? I mean then you can just save and overwrite right away!

Unfortunately no. I know it's a bit of trouble to go trough all that, but if you were to save directly, it will still come up with the an error that you're not allowed to write to that folder.

If you don't want all that you must:
a) Be in the group Administrators as seen via Start>Run Control Userpasswords2
b) Completely disable User Account Control (UAC) via the instructions given on Microsoft Windows Help.

Anyone know how to make color's appear on your mods.
the only one that works properly is the unscoped .44 magnum.
but of course the modder used the original model just massacered the scope.
(sorry if this counts as a double post.)