That's a real shame, I thought they were cracking films. I've experienced that (motion sickness) with the odd FPS game but until last night I'd never had a problem viewing film. I'd recommend you stay clear of Irréversible as the camera work in that made me physically sick - the camera reflects the turmoil the subject's character goes through and needless to say it's a brutal film in every sense - I persevered though as I'd never seen anything like it, it's a pretty unique and rewarding experience.
I started reading the Bourne Identity book shortly after watching the film but found it differed greatly from my expectations. (Note: I'll be honest and say I wanted more of the film's interpretation than that of the original book so didn't really give it much of a chance.) From what I did read though, didn't Ludlum's Bourne fight in Vietman? If that's the case then either the era for the film would have had to change or we'd have had a much older lead actor portraying him - Bourne would have to a least be in his late fifties now and I can't imagine that having a similar impact.