SWAP-Partition ?
 

The Linux installation offert me to make a SWAP- Partition. Is this usefull ? For what is a SWAP-Partition?

It's similar to window's swap file (if you know what that is).
It acts like virtual ram, in case all the apps use up too much.

A swap partition is used to store information that would normally be held in RAM but only whne the RAM is full. Windows uses a file o do this wher as linux uses a partition this helps reduce fragmentation.

So yes it is a good idea to have one. The old rule of thumb was to make it twice the size of your RAM but this isn't neccesary with new machines that havea lot of RAM.

best bet is to create 2 swap partitions, each equal to the amount of ram you have. spread them out between partitions. This speeds up access time, because the heads on your hard drive wont have to travel as far to access data.