Had the same mobo in my last PC, never had any problems with it.
This being micro-atx, with 1 pcie x16 slot, you won't be able to add a second gpu. But then, it's not that great anyway.
400W - 450W PSU should be enough for that specs. If you're ever planning on buying additional HD's, then maybe go for a bit more. Also, high end gpu's can use a lot of power, especially when factory-overclocked.(don't overdo it, more powerful PSU's are quite expensive and loud).
If you're going for Nvidia of the 8000 series, make sure to get one that supports dx10(8600-plus, I think).
Concerning fans, you can run the basic - not overclocked rig with just the GPU and CPU fans, both of which are always(?) supplied together with these. Often there's also a fan supplied with a case. I'll suggest considering buying new fans only when you notice some problems with heat dissipation or if you find those you've got too loud for your taste. In which case, buy large, slow moving ones - those are most silent.
Keep in mind, micro-atx cases are, well, small. It might get cramped inside, and the airflow is inherently reduced. Have you got any specific reason for not getting a regular-sized mobo?(mine was: small cases look better)
If you like this sort of stuff, you might consider getting more than one HD and rigging them up in RAID configuration - this way you can have an instantenous backup running non-stop, or speed up operations on files. Of course, the downside is: you need another, identical, HD that doesn't contribute to your storage capacity(when running as a backup, at least).
Don't ditch your previous PC. Build an immersion-liquid-cooled pc out of it. Loads of fun.(hint: use baby oil)
Yanlin: do not tempt the guy with DDR3, this mobo doesn't support it. Besides, the difference in perfomance should be noticeable only for a *serious* gamer.