Well, in that case..
Yes, Intel is preferred over AMD when it comes to game and framerate performance. I looked around and there were retailers offering some parts for a lower price than novoatalho.pt, but if you don't mind spending a bit more to get everything from one place, I think the difference is maybe around 50-75. I will make some general recommendations. I used kuantokusta.pt to search for general pricing below.
For the CPU I recommend either the i5 4670K (~225) or the 4690K (~245). The latter is newer, but the performance difference is barely noticeable so if you can get the 4670K for cheaper, go for it. The former seems to be selling for a bit cheaper than the latter, about 20 less in some cases. However,
Amazon Spain has the 4690K for 222, which is the best deal.
As for the motherboard, I can recommend Gigabyte, Asus, ASRock or MSI. I would suggest a Z97 model, the cheaper you find, the better. The "gaming" models just have extra marketing and pointless features that you probably won't need. Depending on the price (hopefully around 120), some specific models to look for are:
Gigabyte GA-Z97X-SLI or GA-Z97X-UD3H
ASRock Z97 Pro4 or Extreme4
MSI Z97 PC MATE or Z97S SLI Plus
Concerning graphics cards, it will depend on how high your budget can go, but the Nvidia GTX 970 (370~400) is a great recently introduced higher end model that will last for years. MSI Gaming 4G, Asus Strix, Gigabyte G1 Gaming, and EVGA SC/SSC/FTW are the preferred brands and models. As an alternative, the AMD R9 290 (200~300) may be found for much cheaper and
will perform about the same or slightly slower. The R9
290X is expensive, though.
For RAM, look for the cheapest 8GB sets that are rated at DDR3-1866 or DDR3-2133 (1866MHz or 2133MHz). If they cost a bit high then DDR3-1600 is ok, but 1866 and 2133 are preferred. Looks like 8GB of 1866MHz RAM can be had for about 80.
Power supply is harder to recommend for as I don't know anything about product availability in Portugal. If you go with the GTX 970, you should look for 550-600 watts, and I recommend 700-750 watts if you want to run dual GTX 970 in the future. If you go with the R9 290, 650-700 watts is recommend for a single card, and 1000 watts for dual R9 290. For efficiency, 80+ bronze rating is OK, and modular or non-modular cables are up to you and make no difference except for money and convenience. Except for Seasonic, Super Flower and XFX (rebranded Seasonic), few power supply brands can be said to have all good products and be completely trustworthy. Antec, Cooler Master, Corsair, and EVGA range from bad to so-so to excellent (not in any order) depending on the exact model. Prices would seem to vary quite a lot depending on brand, model, efficiency, wattage, and modularity. Try not to spend more than 80-100 if going for 550-700 watts.
I recommend using something other than the bundled Intel CPU cooler if you want low noise or to overclock, but that can be left for the future. The
Cooler Master Hyper 212 Evo is 47.