o large websites such as gotfrag and gamespot use CMSs because it must be pretty hard to edit all the HTML, and if they do. Is it custom or public. Thanks pr0x.
You should buy or get a couple php books and start up from scratch, you might make your own good cms the way you want it and be able to sell it after. If not use the guys above info haha
It will take you at least a year before you can manage to make your own cms, this is a realistic option but one I would not recommend, there are a few scripts that you can either pay to have customized to what you are looking for or learn how to do it yourself, now that's more realistic and possible option, obtainable within a short (2-3 month) timeframe. Hope I helped.