Atari 800XL and Atari 400

As the title suggests those are the machines I'm looking for.
I had the 800xl when I was a kid and to my mind the design of it is pretty timeless.
On the other hand the 400 is obviously of its time, but as a kid I really coveted it because I thought it looked awesome.
Any tips or remarks are more than welcome. I've always loved computers, but I'm not technically minded at all, so pointers to any obvious mistakes I should avoid would be great.
I had the 800xl when I was a kid and to my mind the design of it is pretty timeless.
On the other hand the 400 is obviously of its time, but as a kid I really coveted it because I thought it looked awesome.
Any tips or remarks are more than welcome. I've always loved computers, but I'm not technically minded at all, so pointers to any obvious mistakes I should avoid would be great.