[Org, Prince of persia]

I played it on a PC-XT clone with green monochrom screen, twin 5.25" floppy discs and a first generation Sound Blaster.

[Van Helsing]

Only if you get to fight an Australian musical actor who's wearing a ridiculous hat.

[Auto Potion for Skyrim?]

Halo Mod for Skyrim.

[...... an arrow to the knee]

I used to be an arrow like you, but then I took a Dragon to the knee.

[what the hell is wrong?!]

Run DPC Latency Tester before the game runs and leave it running while the game runs, hopefully also when it slows down. Post your results.

 

http://www.thesycon.de/deu/latency_check.shtml

[Major screan tearing in sky.]

That's not "screen tearing", that's because you have FSAA enabled but don't have Transparency AA enabled at the same time. You can enable Transparency AA (the stuff the edges of the leaves is made of) in your graphics driver settings Screen tearing refers to VSYNC being disabled causing the screen to show scanlines.

[Skyrim Multiplayer / Co-op?]

Of course, there's also Two Worlds II, which does an admirable job of offering a pretty simple yet enjoyable co-op aspect.