If you're looking to save money:
I would suggest considering getting the i5-3450 as it is ~200KR cheaper than the i5-3550 and the only difference is 0.2GHz/200MHz difference in clock speed.
Here's some cheaper RAM that is probably more reliable and will perform exactly the same as the Corsair Vengeance: Crucial BallistiX Sport 8GB (2x4GB) DDR3 1600MHz CAS9 1.5V (379KR)
It also has the advantage of being 'low profile', so it will fit under large aftermarket CPU heatsinks, if you ever decide to install one, whereas the Vengeance heatspreaders are very tall and would restrict your choice in CPU cooler.
If you want to spend more money then I'd say that it can be a good idea to spend more on the case and/or PSU because if these two items are high quality, durable, flexible and visually appealing (moreso for the case) then they can last for a very long time. I'd personally describe the case and PSU you've selected as good enough components, if you're happy with them then that's good for you.
For a gaming build the most important component is the graphics card, so if you want to maximise gaming performance then you should put as much money into the graphics card.
Thank you for the information!
The budget is approximate so I am more looking for an upgrade rather than saving money. The build is pretty cheap already.
I am going for a lowprofile RAM that you suggest to make the computer more "futuresafe".
Do you have any suggestions on a better case and/or a PSU?