|Poor motherboard choice.|
The graphics & audio are built into the board so if you're not a gamer, a video card probably isn't necessary. If you find that the onboard isn't adequate for your needs, you can always add a card later. Same can be said about the RAM, you can always add more. But if you're going to run a 32-bit OS, more than 4GB is a waste.
I wouldn't go less than 400W for the power supply. Make sure you get a decent name brand unit & take a look at the amperage specs. It's generally better to get a PSU that has a single high amperage +12v rail than a PSU that has multiple +12v rails. Expect to pay at least $40-50 unless it's on sale or a rebate is involved. And beware PSUs with high amperage (more than 30A) on the +3.3v & +5v rails. This a trick some manufacturers use to falsely inflate the overall wattage rating.