The specs are alright, but as others already have told, the Intel chip isn't good for gaming, especially not good for Aces High. You're on a right track with your video card choice, a decent high class card makes good bang for the buck. Again, it's been already mentioned that you'd have to replace the power supply in order to feed the new video card. Also possible measure and cabling issues have been mentioned. Quite many things to take into consideration!
My suggestion is to build a computer from scratch using the dell specs as a guideline added with the necessary improvements.
This is what I came up using
www.pcpartpicker.com for a roughly similar one than your suggestion, only way more upgradable. I believe it should also be a tad faster, although I chose the parts with price in mind just as Dell would... Just add a video card of your choice:
PCPartPicker part list:
http://pcpartpicker.com/p/ZxkfnQPrice breakdown by merchant:
http://pcpartpicker.com/p/ZxkfnQ/by_merchant/CPU: Intel Core i5-4440 3.1GHz Quad-Core Processor ($182.98 @ SuperBiiz)
Motherboard: ASRock H87 Pro4 ATX LGA1150 Motherboard ($84.48 @ Newegg)
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1600 Memory ($88.79 @ NCIX US)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($52.91 @ OutletPC)
Case: Corsair SPEC-03 White ATX Mid Tower Case ($49.99 @ Newegg)
Power Supply: Corsair CSM 650W 80+ Gold Certified Semi-Modular ATX Power Supply ($69.99 @ Micro Center)
Optical Drive: Samsung SH-224DB/BEBE DVD/CD Writer ($16.01 @ NCIX US)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($84.99 @ NCIX US)
Total: $630.14
Prices include shipping, taxes, and discounts when available