You guys must suck. 😉 I forwarded this around to about 10 people in my office and not a single one of them had any problems thoroughly beating it. Granted, many people took different routes. I personally opted for building up my archers first, my builders second and my wizards third (although I didn't realize how important they were being able to convert people at the time.) The most important thing is to save up your money during those early rounds and keep trying to convert as many people as possible. Then you can buy either archers or the mana pool first and start working your way up from there. Once you cross a certain threshold (varies from strategy to strategy) you can start building up your castle walls like mad, althoug you might want to beef them up a little to withstand the pounding from the big guys the first couple times they come out.
A general rule of thumb we all agreed upon during the early rounds is that you usually only need 1/3 to 1/2 as many builders as you have archers to adequately defend your castle. We all agreed the bombers were not that critical to success.