I personaly think the gtx is a waste of money. If you look at benchmarks, the gtx is like minimaly faster than the 7800GT and a 7800gt can be had for around $330 now. Of course we wont get into money, thats up to you.
The brands. I mean really, any brand is going to be fine, as long as its a name brand that has been around a while. Personaly, id say Stick with EVGA or BFG. Im sure most will say this, as they are the 2 top brands always recommended. Both have lifetime warranties as well as great 24/7 and online LIVE(eVGA only) tech support. BFG is overclocked out of box, so it is also slightly faster. Not sure about the evga on that. Either way, both are great. Other brands decent too, but just do not have lifetime warranties.