The good news is that PC hardware is cheap. Quad Core, 8GB RAM job done.
Sorry, off topic... but might be of interest...
On the technology jump subject (a700 to a900), well I've now upgraded my old SD Video Cam (Sony DV, PAL 50i) to a HD Video Cam (a Sanyo 1080 60p). Sony Vegas Movie Studio used to render 10mins of SD video in around 3mins (Quad 3.0Ghz, 8GB RAM). Now with the same hardware, Vegas renders 10mins of 1080 60p video (mpeg4) in approx 1 hr (that's a 20x performance decrease)
There does look like light is at the end of the tunnel with HD video, since it appears that companies are using the 'PS3 Cell Processor' for speeding up HD video editing (as a Co-Processor). Anyone remember Co-Processors?
The move from the a700 to a900 was nothing. SD to HD video is on a different planet.