Thanks for the info Harrison. That's what I'll probably use - I'll get much better quality too!

I never knew about that Stage 6 site - looks interesting!

I went back to an earlier install and the issue lies with Flash 9 and Firefox 2 on these machines. Tried disabling hardware acceleration on the graphics cards and in the Flash settings to rule out a conflict, but it made no difference.

Internet Explorer with the ActiveX Flash 9 has much lower CPU utilization. 20-30% on playback, 1-3% on a paused embedded player and about 20% for animated menus. That's both on YouTube and my own ClassicWB Features page. About what you'd expect and what I was getting before recent software updates.

Nothing I can do really - YouTube needs Flash. All I can hope is that Firefox 3 and Flash will work better on these two machines, or I may have to go back to Internet Explorer - especially on the Laptop.