Yeah, there's definitely nothing wrong with your machine, IMO. I've got an AMD 2100+ with 1GB RAM and, like I said, I burn at 8x with no problems whatsoever. As long as the rest of my machine isn't taxed too much, I'm fine.

Frankly, I'd never in a million years use anything made by Ulead. Ugh. Try the Nero demo and see if it auto selects a higher speed for you.

Are you only burning the MPEG files, or a DVD video you've created?