atiumdag.dll has nothing to do with glide

the gog version comes with openglide i believe so use that instead of nglide

I used Glide2x.dll version from nglide (~1,2mb - in win7 x64 copy from c:\windir\syswow64\) and efect the same - "Failed o Initialize...".
Also i try this (from gog forum)
"Problem: The game crashes with an error 'Failed to Initialize 3D hardware acceleration'.
Possible workarounds: Some speculation exists about this being related to ATi Radeon cards. Rolling back drivers might be a temporary solution, as proposed by ZamFear.
Update: ZamFear found the offending dll file! The fix proposed is to drop an older version of this file into your I`76 directory. That way you don't have to roll back system-wide drivers. A copy of the driver was graciously uploaded by Manfromx. Though the file came from a 64-bit installer, chances are it's a redundant file that works for both 32 and 64 bit OS installations. [ on gog forum link to the ATIUMDAG.DLL file was dead]
Because I`76 ran best with Glide (a now defunct driver set for the old 3DFx cards), a Glide wrapper (emulator that lets modern video cards run glide) is required for optimal performance. Unfortunately, not all wrappers work with all cards on all systems, so the GOG included OpenGLide might be sub-par for your system. Trying a different Glide wrapper might be best. DosFreak had some good suggestions here.
Try DgVoodoo
Zeckensack
NGlide
In that order. Also for DgVoodoo try different DirectX modes. The first 2 are lights years beyond OpenGlide, I only use OpenGlide as a last resort.
Note that the DgVoodoo result on Google is current a page that's blocked, and apparently serving up Trojans and virus downloads, so it's to be avoided for the moment. An alternative download link can be found here.
Software mode might still be possible under these conditions, but will likely be buggy and look nasty. Framelimiting isn't as straightforward on the software renderer. "

I try everything but i dont have file from catalyst 9.5 - ATIUMDAG.DLL... so i think this is a problem... or maybe i'am wrong,,,,

Maybe you can try this:

http://www.localditch.com/interstate-76/downloads.html

I played this game a while ago with dgVoodoo or Zeckenzack's, can't remember. Be sure to read the faq on the site, it's helpful.

thx but i found this website when i was searching about Interstate ’76 problem with hardware acceleration.
Game from GOG - Interstate ’76 Arsenal is the goood, old game I76 but already patched to running the game under Xp/Vista or 7.
Anyway thx for intention...

ok try this
uninstall your catalyst drivers
make sure you delete any ATIUMDAG.DLL from your hard drive
install catalyst 9.5
copy ATIUMDAG.DLL somewhare
uninstall catalyst 9.5
re install the catalyst version you want or stay with 9.5
bingo you have ATIUMDAG.DLL 9.5

ps: what video card do you have ?

i've ati 5770 - but i dodn't want to reinstall my ati driver - at the moment i use catalyst 11.3, and i dont know that catalys 9.5 detect my video card...
yesterday i download catalys 9.5, i started install bud when ati decompres files i quit installation, i have found ATIUMDAG.DL_ and with command "expand -r" i extract dl_ to full DLL file.. copy the file to my I76 dir and i have the same error " failed to initialize..."
maybe expand command didnt work correctly...

have you tried other wrappers escpecially the ones that use opengl not d3d
and why not installl cat 9.5 your only doing it long enough to get the file you want
you can then go back to 11.3

Thank you so much!!
It's really a driver problem from ATI.
I uninstalled my previous drivers, and Windows 7 automatically reinstalled the old ones from 2009.
Interstate 76 now works great using nGlide v1.00 both D3D and Glide/3DFX (in D3D it's slow, so I stuck with 3DFX).
Tested my other games and everything is working fine (Carmageddon with Glide Dosbox, NFS4 High Stakes in Directx9b mode).
Seems like we ATI/AMD users just can't update drivers.

My hardware is: notebook loaded with ATI Mobility Radeon HD4650 DDR3 512MB, Windows 7 32bits