New DDR3 Memory for Mac Mini I bought a Mini last year and I want to update the RAM.

I was shopping around to find some compatible memory and found (this)from a Spanish retailer. They are selling what you see on the picture and I'm trying to understand if this memory is compatible with my machine or not.  I wrote to the company and they said that there will be no problem but I want to be super-sure.

This info is about my mac:

2.3 GHz Intel Core i5
2 GB 1333 MHz DDR3
And running OS X Lion.

Can anyone let me know if this memory is definitely compatible? Or advise on what else I am able to use?
You didn't actually specify the model of your Mac Mini, but by going off the data from here, I think you have the mid 2011 model (Mac Mini 5,1).

If that is correct, then Apple's technical specifications on this model confirm that the Mac Mini uses 1,333 MHz DDR3, up to 8 GB (4 GB x 2).

HOWEVER, that memory that you linked to is "DESKTOP" MEMORY, a DIMM (dual in-line memory module). The Mac Mini uses "laptop" memory, SODIMMs (small outline dual in-line memory module).