|"The latest processor this computer will take is an AMD K6-III+, which was a competitor to the Katmai P3s."|
Katmai was nothing more than a Deschutes-cored Pentium II with SSE tacked on. Intel even called it Pentium II a few months before its debut. The Coppermine was the first real P3, and it was considerably faster than Katmai, especially in NT-based operating systems where cache performance actually mattered. When jackbomb mentions the P3, he means Coppermine or Tualatin, not Katmai. :)
Flash seems to like memory bandwidth as well as SIMD performance. Thanks to an on-chip L2, the extra bandwidth available to the K6-3 will boost Flash video performance a little. However the very weak FP performance (compared to the P3/Athlon) and lack of a proper SIMD instruction set to make up for it (K6 lacks SSE, and, let's face it, 3DNow! is a joke), will really hurt Flash performance.
If you want to watch YouTube video on that machine, you'll have to download the video to your hard drive as an MP4 file and play it in a DirectShow media player (Media Player Classic, WMP, etc). DirectShow is a far more efficient way of playing back video than Flash.
Samsung 1080p panel
2 HDMI, 2 Component, 1 VGA
120" 16:9 screen
Connected to: HTPC w/ BD, satellite receiver, XB360.