i myself can understand the 2 system setup, loads of members do it infact, maybe not gaming based as such and im sort of the same, well was untill i sold what i got as money needed(i build/upgrade computers), but one was more for testing and the other for games/movies, but having a windows 8.1 computer a lot of games of old i have(more old school gamer) either dont run or doesnt run well due to compatibility, so i will be looking for an older but nothing fancy computer for such games...
my advise would be if you have a computer thats oldish and has issues then fix/upgrade that for low en dand save up for the high end or just go on ebay/gumtree and buy a computer for 45-60 and just add the required bits if needed..
When I got the laptop a few years back, I decided to have everything I had installed on it so depending on what one I was using, I still had access to everything (although saves weren't the same on both) but limited space on the laptop (it only has a 250GB hard drive, and before I put the GT610 into the desktop it had more graphical power) meant that I had to remove games from it so I could have a decent buffer when I installed other games which is why I decided on this split build since a majority of what I have doesn't need that much graphical grunt, and the rest while some wouldn't be able to run or run in low settings they will be able to stretch their legs once the more powerful system is built (please excuse the wall).
The other problem is that even if I tried to get around the known issues with the desktop, the main issue is that the processor is at least nine years old and will have the crap kicked out of it by any other currently available equivalent processor (and will most likely get teabagged at the end) which is why I decided to use more current components (the laptop will still be used since it contains my whole iTunes library, and the desktop can still be used and could probably be wired to a TV (if I ever get one since it can't be connected to my current one) and used to play media either locally or through a network attached device).
I might eventually build an ultimate gaming system (that could be a challenge for those here to come up with 2 options (one with an AMD processor and the other with an intel processor) no expense spared but not an overkill system), but that is only going to happen when I actually have the money (I'd most likely be able to build the low end system and a budget gaming rig with the money required for an ultimate system and still have change left over).