psu: that 450W psu will be enough unless u plan on using SLI
processor: I'd get a better one. the fx series kick some major butt in gaming, though it is damn expensive. I'd go with the x2 4400+.
Single cores are better at gaming atm but soon most of the games will take full support of the dual core processor. And the dual core is way better at multitasking. Or then go for the athlon 64 4000+ if u want a single core processor. But I'd take the dual core.
cooling: U will be fine with the air cooling, but if u are going to oc then that water cooling kit will come usefull. And from what I understand it is already installed so no worries there.
mobo: that seems like a good choise to me.
ram: yes 2Gb is the way to go. And yes, I would go with the XMS, I just don't like the value ram.
vid card: If u can afford it go for the 7800GTX. If u can't then look for cheaper options. The 6800GT is also a very good card, though I have seen some ppl experiencing some problems with it.
Raid stuff: I don't know what that raid controller is. But those raid setups (raid0 and raid1) are used to improve the harddrive performance. U need to have 2 hdd's and then when they have raid0 setup they somehow work together to improve the speed. Since it seems to be free (?) if u take 2 hdd's then I'd take the raid0 setup. If I'm talking just crap here someone plz correct me