I haven't looked at prebuilt systems in forever. Building your own is really the way to go. It's more assembly and can be done easily. If you can do simple maintenance on the Ti you can put some parts together. Check out
http://www.reddit.com/r/buildapc for planning as there many of them know what works best for your needs. I am also quite knowledgeable in the hardware field. With that main thing is your budget. From there we can see what is the going to be the best bang for buck. Do you just need the PC or do you also need new, monitor, peripherals, etc? Is this going to be strictly for gaming or will you be doing editing/ other intensive tasks? What resolution will you need to be pushing? What games do you normally play?