Dont think there is a special good time to get a PC.
All i suggest is that you dont buy the best of the best, that gets very expensive. Cheaper alternatives can do the same job, you're paying for the novelty that its one of the newest toys.
@archangel or something like that:
So I say now is as good a time as any to buy the parts for a computer, but if you wait a few months, prices will drop on the high end stuff right now. The 750GB hard drives will drop from 250 to like 150 dollars, and various other prices will drop 25 - 35 dollars.
It's all about, do you want it now, more expensive, but you get 4 months of enjoyment out of it and more? or wait, and save a few dollars.
The thing is in a few months time he'll want the latest which will be expensive. Like, if he wanted to buy a computer 4 months ago and get Dual Core, and he had waited till today, sure they cheap. But 4 months on (which would be now), he will start wanting a Quad Core. Just gotta make a decision.
Oh and Christmas, prices dont go down, they go up! In Australia we have like a week of sales after christmas getting rid of all the christmas stock. dont know if in your country/city they have something like that. I would just buy it now and do your research. As someon else said, Newegg isnt always the cheapest. Check Froogle, Frys, Newegg and some price comparison sites.
For example, Getting a E2140 (dual core) and overclocking it to 3.0Ghz (with good cooling) is easily done and its about half the price of the E4400.
Take it easy.