I am looking for game changing mods. And not just new content added to the vanilla MW or new places but something like a WHOLE new game. Something like Nehrim (I can't play Nehrim because my PC is too bad). So are there any out there? Please recommend some.

Do you mean like http://www.tamriel-rebuilt.org/? Maybe combined with the mod whose name I forget that allows you to start there? It might have been http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=5682. I can't remember.

I've never played Nehrim, but a quick Google Search shows it'd be a bit different to TR. Mainly as TR is set to complete Morrowind by making Morrowind mroe than just the island, so it's not a "whole new game".

So, what you're after is another game made in the Morrowind game engine? I hate to say it, but why not just play another game? The only one I can think off of the top of my head that would potentially fit the bill is one that is not well thought of, http://www.fileplanet.com/149635/140000/fileinfo/From-Hell-to-Heaven,-Morrowland. I warn you though that it's not well thought of for a reason.

@OP
You mean total conversions? There are two TCs made by the same team as Nehrim (SureAI):
http://www.gamesas.com/index.php?/topic/991476-beta-relz-arktwend-tc-translated-to-english/page__view__findpost__p__14330282

Here is the current thread for Arktwend: http://www.gamesas.com/index.php?/topic/1067645-relz-arktwend-english-31/

Thanks! I downloaded Arktwend and I'm currently really enjoying it! Doing the mission where I have to get the fishing rod to get across the border currently