It also depends on your connection and the nodes you are connected with, but you should be able to download the entire block chain within 48 hours. Nowadays HDD space is very cheap where you can get yourself some great deals on 2,3,4TB disks. That should be enough for the coming years.
I have a 1 TB HDD so it should allow me to continue for a few years I guess? But the problem is that the bitcoin core slows down the computer- I can only do minimal things with the computer.
I also have a 1TB drive and you are right, it does slow down the computer quite a bit while Core is active in the back ground. But that's mainly due to the HDD being the bottleneck here. I am planning to buy myself a large SSD since the price of these drives gone down significantly. That will definitely help speeding up things.
