Mine has always been horizontal. It's right on top of my dresser next to my TV. When I first had it, it was scratching my discs. Then I seriously procrastinated for a whole year (maybe more), and I finally sent it to get repaired. It arrived back the day after Fable 2 came out, so I was stuck with that glorious game and no Xbox for a whole day.
It was totally fixed though. Oh, also, I used to have my Xbox plugged into an outlet that the plug would fall out of pretty easily. On two separate occasions, the plug fell out while I was playing, and the RROD showed up. I freaked out both times and hit the power button to turn it off. I was able to turn it right back on afterward, and everything was fine. The first time, I didn't realize that it was the plug that caused the RROD, but I did the second time, so I plugged it into a different outlet. Nothing bad ever happened, and I've never gotten the RROD since.
![Frown :( :(](https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f641.png)