I learned that Win 7 likes more RAM, although it runs with 4 GB. I took 8, since it is
cheap. You can get it for 20 bucks per 2 GB.
GFX board - don't buy the latest and newest - it is overpriced by 200%, and one year later you see it in the shops for a third of the former price, and then enjoy the rest of the day

. If you spend 550 bucks for just GFX, then nobody can help you

Look for a good offer in the 100-150 Euro range. For example the GTX460 gives you nice performance, and the 512, 768 and 1024 MB versions cover that price range (I personally prefer nVidia due to bad experience with ATI and its drivers some years ago).
Avoid MSI mainboards, my research showed not really favourable reviews, but many problems with instabile BIOS. An older system of mine also had an MSI board, and yes, already ten years ago MSI was known for having not the best BIOS. Asus is a good choice. My new board will be Asus, my old one is Asus as well - having run for many years now. It and the Pentium on it are the only two things that in my old system have not been changed at least once in that time.