I agree about the GTS450 and Blizzard games (WoW, StarcraftII and most likely DiabloIII) You should have no problems with most Micro-ATX motherboards unless the card covers a SATA port or 2, in that case get 90 degree cables that fit.
In terms of brand look for a good warranty.
EDIT ...If it's the MSI motherboard i think it is, the SATA ports are already turned 90 degrees, so you wouldn't need new cables.
i run a asus Top direct CU gts 450, i can play WoW and starcraft 2 at ultra settings, my wife has an evga rerence 450 (not overclocked at all yet) she can only play custome first set to ultra then with the shadows down to low , 2xaa , and i believe enviromental detail to medium , this led her to 50-60 fps, while mine does 60 fps all the time
basically any gts 450 card with a good factory overclock with run either in ultra, if you get a refrence cad you'll have to dial it back some
and palit isn't bad per say, they can be quite good, but some of thier earlier cards were iffy, i've handled a never 460 installing for a friend and it was very stout on a nice custom pcb and cooler, the 450 they do with the shorter pcb and big fan is a very nice 450... adn thier refrence card is refrence so its the same as all the other refrence boards. its a good choice