I downloaded the hi res texture pack from steam but I can only play skyrim on high settings. Should I be using it?
The biggest issue with using the high-res textures packs that I had was the amount of VRAM on my video card. With one Gbyte, I got stuttering, frame rate drops, textures that didn't load, etc. When I upgraded to a 2 GByte card, most of that stuff went away.
Post a Dxdiag with your system specs.