Is AE CS3 ready for HD?

I am working in 1920x1080i. I have a comp that simply will not render. In fact I have never been successful in rendering an HD comp. My last project I ended up lowering the resolution until I found something it could render. I'm on a Dell 4600 with 4GB of RAM, (not that the amount of RAM is important since we are capped at 2GB.)

I decided to keep simplifying my latest project until I got all the way down to 1 light, 1 camera, and a 3D text layer with motion blur. Still unable to render. Anytime there is fast movement I have observed it cannot be rendered. If I constrict myself to 2D, no motion blur, & no camera then I have no problem. Unfortunately this makes AE useless for my work.

Great tool for SD but I am not finding it useful in HD. The project I am on now I have been experimenting on for 24 work hours & it simply refuses to render the final 2 frames because I have this text layer rapidly rotating on Y as a wipe transition off the comp. I cannot complete the move. I am now faced with redesigning the end of my open.

I am a bit frazzled as this is costing me serious time. Has anyone encountered this & anyone from Adobe has a clue what is wrong?