I am using a Mac Mini for live broadcast streaming. I am using Wirecast for the encoding. I am encoding the stream in Flash format and I'm simultaneously recording to hard drive in QT h.264 format. This maxes out my 2 GHz Core 2 Duo mini with 4GB RAM. I am trying to decide how I might improve my setup for optimal performance. For example:

1) Should I replace the 5400 RPM internal hard drive in the Mini with a 7200 RPM drive and continue to run the broadcasting and recording as before but now with the faster drive? In other words, would I expect meaningful gain by simply upgrading to a faster internal drive?

Or:

2) Should I add an external 7200 RPM 800 Firewire HD to the Mini? If I do this what would be the best way to utilize the faster drive--
a) Booting the mini from the faster external drive and recording to the external drive and essentially "ignore" the internal drive?
b) Boot from the internal drive and use the external drive for recording the movies?

I guess what I am really asking is this-- Will I have better efficiency in performing simultaneous encoding and recording by off-loading part of the work to a second hard drive?

I assume that the encoding of the broadcast stream is determined by the CPU and is independent of the hard drive configuration.
Any suggestions will be appreciated.
John