Your 206VA rating is assuming a 100% efficiency rating which isn't going to happen.
Another thing. If you only have limited knowledge and no experience with Switch-Mode Power Supplies, I would recommend that you do a lot of studying and reading on the subject and also become very familiar with High-Voltage saftey measures. The voltages and currents commonly found inside a SMPS can kill you instantly 1000x over.
That being said. You could build a 500W half-bridge supply quite easily to get the power levels you are looking for. This could also be done with a 2-switch forward converter topology as well, although I think the half-bridge would be easier to configure for a beginner. I would also recommend a "hard-switched" power supply for this power level and because they're easier to get working for a beginner.
Here is a link to a website showing the different topologies of SMPSs and it also offers some calculation help as well, although I've never used the calculations on this website before.
http://schmidt-walter.eit.h-da.de/smps_e/smps_e.html
Also, for figuring out the number of turns and other design factors for your switching transformer, I've found the program in this link to be very helpful. I think this program was created by a fellow user here at diy-smps.
http://www.diysmps.com/forums/showthread.php?275-SMPS-transformer-design-tool
Good luck in all your adventures into SMPS design and above all...BE CAREFUL when building and testing these things. DEATH IS PERMANENT!
Also, if you don't have an oscilloscope, don't even try to build a SMPS. I've managed to get a couple working w/o a scope, but it was nearly impossible, and I blew up many components on the way. All I had was a frequency counter and duty-cycle monitor and it took me forever to get one of these PSUs working. Once I got my scope I was easily able to diagnose problems in the supply. Also, if you have a scope, become very familiar with the proper way to take HV measurements and be very careful where you place the ground lead of your probe. Also, NEVER try to connect/disconnect a probe while your "device-under-test" is running. If you accidentally touch the probe in the wrong spot, very bad things could happen, like blowing up your scope, your power supply, or death. I would suggest, even insist, that you either buy or build a differential scope probe so that you can take floating measurements between two points above ground. Here is a link to one I built myself from scratch because I couldn't afford one. They are very expensive for a real one, but they may save your scope and a lot of headaches.
http://www.diysmps.com/forums/showthread.php?511-Built-a-Differential-O-Scope-Amp