The cpu is essentially the brain of your computer. The more Mhz it has the better it's capacity to use and run your programs. Mhz is kind of like speed. The more Mhz you have the faster the CPU is able to deal with what you have working. The more Ram you have is also better.
Ram is memory. The more Ram you have to feed the CPU the better it works.
So in answer to your question, yes. 850 Mhz is the bare minimum you need to run AH. 2 Ghz or more is better.
Minimum Ram is 256 MB, but more of this is better too. 2GB of Ram should keep your CPU fed and happy.
I suggest googling your queries as well. You will get a much better understanding than I could possibly put across to you here.
cheers,
RTR
oh, and here.... , .. '' ? .
Just a few punctuation marks I had laying around. Feel free to use them if you wish!