Hmmmm....I like the looks of the system.
If you go with multipler harddrives, a CD-RW, and a DVD, plus some case fans and a good quality heatsink, you MIGHT want to consider a 330 or 350W power supply. If it is not too much more $$$, than you might be a little happier with it.
However, since you said you won't be overclocking, then you might not need too many extra fans. The TBird cores do get hot, so you will need to make sure you have at least an intake and exhaust case fan (not including your powersupply fans).
If you just go standard setup - harddrive, CD-RW, and no overclocking, than 300W should be fine. I personally have two harddrives a CD-RW, CD-ROM and have gotten bitten by the overclocking bug. I currently only have an intake, exhaust, and powersupply fans plus a wimpy heatsink fan. I am buying a poop-load of fans (5 total) and a new extreme heatsink fan, so I will be seeing the limits of my 300W powersupply.
I'm getting a bit off track.
The point of this entire post is this: DO NOT TURN DOWN A FREE UPGRADE TO A MORE POWERFUL POWER SUPPLY. You probably won't need to go out of the way (ie. lots of $$$) for one, but don't shy away if its only $10 more.
OC Knight of the OC Crusades