The Sony A-100 does not offer any significant improvement over the KM 5D, and the current price of the A-100 is justabove the level of consumer DSLR cameras. The A-100 does fine at ISO settings below 400, but generally folks are expecting more ISO cabability than ISO 400.
I am really not sure how true is that mtclimber
According to most people around, the Sony A100 was certainly a significant improvement over the KM 5D. The only thing that is bugging is anything above ISO 400 > ISO 800 - ISO 1600. From what I can see, the ISO 800 isn't bad and the ISO 1600 isn't reallythat bad. (The ISO 1600 shots will benefit from some post processing.)
Regarding price, I don't know about your country; but it is selling for RM 3200 here in Malaysia. That should be about 888 USD approx including the kit lens.
The A-100 does fine at ISO settings below 400
The A100 actually does fine at ISO 100 - 400. After those levels, it then gets quite noisy and then noisy at ISO 1600.