Personally, I think that in the future other cryptocoins will have success, too. ETH is a likely candidate.
But anyway.
Thanks for all the useful input, everyone.
I'd like to try and mine some ETH.
Do you think a "MSI NVIDIA GeForce 8400 256MB GDDR2" is too old to be any good?
In my opinion its not worth it just get a new card for mining.