Thing about the PSU is that you want something good, but not too expensive. But you should also get something that will handle an upgrade to a DX10 vid card, it's not like a PSU for that will cost double. So really it depends on your budget. A GOOD 600watt PSU should do you just fine for a few years. And trust me, an extra $30 to get a better PSU is a VERY GOOD investment. Don't bother spending hundreds and hundreds of dollars on a system and then try to save $30 on the PSU, that's insane. About how much $$ you got left for PSU?
OH, and are you in Canada or US?