Hi
This is probably usless advice but I do like the sound of my own opinion and you have posted twice!!
It would help if you explained what you mean by ‘not smooth’.
Does your video card support Open GL? If not then the image is rendered by S/W and that’s going to be slow, possibly erratic (not smooth?). PI would have whinged at you when you first loaded it, do you remember a whinge? There may be a help function in PI that tells you if it is using Open GL, I’m not at my machine at the moment so can’t direct you.
Your RAMs OK – You should be better than 1.5GHz on the PC at least I guess.
Hope that helps!
James