(You didn't mention a video card, you should check that before you start shelling out for games. Some of the i5s have intel graphics and you won't be able to play very many games if that is the case)
If you liked Age of Empires, you will probably like Rise of Nations. In my opinion, Rise of Nations is actually better. Rise of nations is similar to AoE in that there's a bit more emphasis on development than your ?craft/C&C types games. You progress through multiple ages, you have wonders, you have multiple resources. If you liked those parts of AoE you will like RoN better because it has more ages, more wonders, and more resources :D (IIRC there's 5 in RoN vs 3 or 4 in AoE)
As far as jRPGs go, if you haven't played The Last Remnant, it's worth getting. It's not like THE BEST GAME EVER but it's probably the best jRPG I've played. Has a pretty cool battle system that is based on unions (groups of up to 5 characters) instead of individual characters. The story and setting are a bit lacking, but they usually are in jRPGs!
Now, some other games that I don't know if you've played but everyone should include:
Half Life (The whole series)
TES Oblivion (Gotta prepare at least a little for Skyrim, right? :D)
Fallout 3 (I am too poor to get NV but I hear that one is good as well)
Borderlands
Crysis (This is just a pretty OK game, it's not bad but it's not great. This is mostly because it's the quintessential benchmarking game now :D )
As far as Call of Duty goes you definitely don't want to get any of them unless you go CoD 3 or earlier >.>
So, I realize that the newest game in that list is 2009, but the field of games has been really bad. On the bright side, Battlefield 3 and TES Skyrim are coming and they might just be good enough to make up for 2 years of shit :D
