A couple of things, you live in Edmonton right?
If so, there's a memory express up there and they will price match NCIX's prices. I think they will build it as well, but i'm not sure what the pricing is on that. That way you save on shipping. You should check it out.
They will also price match ANY store in Canada. So, use Shotbot.ca, put in your parts and look for the cheapest price BEFORE rebates. (they won't match rebates)
I would spend another $30 on the CPU to get the Q8400 (quad core)
I would also look for good deals on ATI 4770 (it's almost the same as the 4850, slower in some cases, faster in others)
If you want to do more research, bit-tech released their monthly buyer's guide.
http://www.bit-tech.net/hardware/buy...should-i-buy/1
Oh... if you know anything about installing OSs, I wouldn't buy the Vista software. Instead download the Windows 7 RC from microsoft for free and when Windows 7 is released, buy that.
I'm probably biased, but I love Windows 7 over Vista.