I'm going to be in the market for an imac very soon, dont have the cash for a new one so i will be looking for second hand, ive never had one before so dont really know what to look for ? any advice? what can i get with 300-400 ?? pentinum? i am literally clue less, if i get on with it i presume i will end up getting a new one eventually but i want to see if i like it first, advice appreciated, thankyou.