And for anyone struggling.

For all those who will proberly find the game to hard here's a set of cheats to make it more easier on your brain.

Bring the console up with [~] and type the following codes in.

aviDemo = Saves a demo of your playing to an AVI movie file
benchmark = Game Benchmark
doomhell = Skip all levels to last
freeze = Freeze all on screen
gfxinfo = Graphicscard infomation
god = God mode
noclip = No Clip
notarget = Invisibility to most enemies
com_drawfps 1 = Show FPS
give all = Full load of weapons and ammo
give doom95 = Load the '95 version of Doom
give keys = Acquire all the keys you'll ever need
give weapon_machinegun = Machinegun
give weapon_shotgun = Shotgun
give weapon_plasmagun = Plasmagun
give weapon_bfg = BFG
give weapon_chainsaw = Chainsaw
give weapon_rocketlauncher = Rocket Launcher
status = Your game status
quit = Quid aka Exit

lol nice one shane. I didn't find i got any tearing at all. It all looked very nice at 1024 in High detail. Only slow down i got was going into new rooms, which I presume is the loading of new textures to my 128Mb GFX. I'm sure if I had a 512Mb card i wouldn't have this prob

The tearing without vsync annoys me, dont know how people put up with it. Its not always very obvious, depends on your fps and how much movement there is on the screen.

In your DOOM 3 directory, find "DoomConfig.cfg" (x:\Program Files\Doom 3\base). Open DoomConfig.cfg in Notepad.

Find the line:

seta image_cacheMegs "32"

I changed 32 to 96.

I got a nice boost in performance. I dunno if the tweak worked or not (maybe my machine did something wierd, have no clue), so I'm just seeing if this works for others as well, or if a different setting works better than others.

you can try 128 and 256 aswell

i tried 128, got about 5% improvement on High, still want a new Card though