My friend is getting a new computer put together and i had a question about the power supply. He's got an AMD Xp1800, 256mb of ram, a 64mb video card, 2 cd drives and two hard drives. I'm assuming that his current 250 Watt PS isn't going to cut it? Will a 300 Watt be ok?

Also, what if we just install 1 HD and 1 Cd to get the system up and running, and then add a bigger PS and the other components later?

thanks.