Buying a surround audio system

[Elenneth89]

Hi folks.
I'm checking the stuff to buy for building my new computer, and I was a little bit unsure about the sound aspect.
As a laptop owner, I've always used headphones so I'm not very aware about external sound system.
I was looking for a 5.1 system, possibly of a good brand (Logitech et similia).
The budget is around 100, 150€ (is this enough for a good one or do I need to invest more money?)
I live in Italia btw, so I need something suitable for this market.
I was thinking something like Logitech z506 or x-530.
Thank you for all your kind help

edit
The room is 2,5 m X 3,5 m

edit v2
I'm getting also a Asus Mod 1150 z97-k as a mb.
Do I need an audio card or not?

 

[nostall]

I took a look at pcpartpicker.com for both England and italy and could not find any good 5.1 systems in your budget range, so I can't help you with that request; however, I purchase a Logitech Z506 set up for my son a few years ago, and the sound quality was so bad that we had to take them back. The replacement set was a Z540 (for the same money) and they sound pretty good.
Don't think Logitech makes the 540 or 530 set anymore.
If you are truly serious about 5.1, then save up a bit more and look at the Z906 from Logitech if you can find them in your country. AmazonUK had new and used 906 sets; but I would think (could be wrong) that the shipping would be prohibitive.