I've been a console gamer my entire life, but recently, wife got me into the Total War series and now, I'm hooked on series such as Total War and Mount and Blade. The only issue is I'm using my labtop to game which doesn't exactly have the best processing power. I get 10 FPS on Shogun 2 LOWEST settings, and I even lag in Medieval 2 Total War, which was released in 2007.

My wife had a daughter less than a month ago so I am on a budget. My tech knowledge is near zero, so I need to buy a pre-built one.

http://www.bestbuy.com/site/iBuyPower+-+Desktop+-+8GB+Memory+-+500GB+Hard+Drive/6980021.p?id=1218818471270&skuId=6980021. I know it probably isn't that amazing, but I don't want to play Crysis or Arma on high extreme settings. All I really need is the ability to play Shogun 2 Total War and Rome II Total War on decent settings with no lag.

Can someone with some computer knowledge tell me how good the linked computer is, and all in all, what is the best deal I can find on a decent gaming computer?

It's crap. The GPU wasn't designed for gaming at all.

As I expected, considering it's only 519 dollars

I'm of the opinion that if you aren't willing to spend at least 900 dollars, then don't bother with a gaming PC. You can build a decent PC for less than that, but you'll be scrimping on something and it's just not worth it. You don't just want something that can play the latest games now, you want something that can be upgraded in the future. So your case and PSU are very important. Don't get a cheap case and PSU. If you're considering getting a pre-built gaming computer, then maybe reconsider getting a gaming PC at all. Pre-builts are stunted, overpriced, and generally not worth your money at all.

EDIT: What you linked to will likely play the games you mentioned fairly well, but that's about it. It's a crap PC in a fancy looking case, and won't be any good to you beyond the occasional game of Shogun. My advice would be to save your cash and get something decent.