there are 3 or so other plans for complete power supplies floating around, at least one of which uses the maxim route (sproggy)... I'd just look into those options before you go into the long road of designing something yourself. It's very complicated and a lot of things have to be taken into consideration.
Do a search in the forums and look for other DIY (do it yourself) power supplies, also check out some of the retail ones available, they're not so expensive. If your time is money then it's probably worth just buying a retail one (you get warranty too) because you're looking at a lot of hours pouring over plans, buying parts and doing the work to get it together.
But don't let me discourage you from the DIY route. I was going to do that, but I think I'm relenting because it looks like there are some cheap retail power supplies finally coming out. Additionally the inverter route is working fine for me in the meantime.