Powerlogix has a special upgrade on their site that their resellers do not carry- Dual 933 for $799. I figured it was a god deal and bought one and it's great! I upgraded a QS733. The OS feels extremely fluid! Scrolling in Illustrator is super smooth, where before it was very choppy. I timed some common tasks and the improvements were definitely there! The biggest improvement is the OS and how well it flows and how switching between apps is as snappy as 9 was! Some people have noticed wake from sleep issues, specially on the 100mhz bus systems, but this one went well. Just thought I'd share the experience.