it looks like you have a fair amount of power-hungry devices there...
First of all, the 1Ghz TB will need a good power souce,
then you have the CDRW which needs good power too,
2 hard drives...
AGP card...
it doesn't hurt to go for the 350W as I don't think it'll cost you that much more.
More importantly, is the brand you get. If you get a crappo brand 350W..God knows if you really are getting the 350W out of it and the quality of the current too...
As suggested by mr-evil, get the Enermax. It is one of the best branded PSU for PCs. I have the 450w Enermax myself.