Nice setup, is the Radeon 512MB? Ye? Than you should get another and crossfire when your bro gets his next cheque (if he's still feeling generous!). Than we'll have the same *general* specs apart from the ATi part.
I've had my rig for a few months now so i've been on the hunt myself AND since im running mine dual-screen i normally let the HDTV take precedence over the LCD (even though my HDTV is older and can only run @ 1024x768). AND since im on a leather recliner here i yearn for a controller as opposed to the usual kb/m set-up.
From what i have seen your fairly limited in options, especially since your narrowing down your search considerably when taking a controller into account...
Get Pinnacle Game profiler if you can.
I downloaded a 'profile' for CS:S & S.T.A.L.K.E.R but as i expected (unfortunately) some PC games just have too many buttons... but with that being said, it's a great app to use a controller with.
Of course i have to mention Crysis & Crysis Warhead too. They have 360 controller support built in (though you'll have to sort out the crouch button yourself.) so they are sure winners. If you can give an FPS a chance than give the first Crysis a chance, the second one is alright.
Again, i know you don't like FPS, but for like 15 mins just get over it and go pick up a chicken near the radar jammer (at the start) and fuck it out to sea with a touché of super-strength. Giggle than play till end. I played Crysis with the 360 controller from start to finish, works a treat, just sort out that crouch toggle.
I can vouch for Dead Space as well. It looks killer, literally, with everything cranked up to full. You'd expect the loading times to be better on a PC? Well sadly, no. But thats a small inconvenience. [you really need to up the res on this one, i chose to play it on the LCD because of this]
I know your looking for action games that use a controller but still, i have to mention 3 other titles that will push your PC;
World in Conflict
Men of War
Supreme Commander
I know they are RTS's but just grab a hardback book and use your mouse on it (buy a decent wireless one). You won't need a keyboard (apart from shift) for Supreme Commander anyway.
Burnout Paradise, as someone else mentioned, is available for the PC. I have that here and it looks great (bikes especially, as a matter of fact i only play with the bike's). Like Crysis this one has 360 controller support out of the box which is helpful. Unfortunately, this game isn't really that good if your into racing sims; i like forza and i hate the handling in this game, too arcadey... no manual shift?!
Oh and in terms of getting a racing wheel, i have a wireless receiver which i use to connect my 360 controller to my PC. I have the 360 racing wheel here (which is the best one ive personally used for a console) and i know for a fact that i can use it for other PC games cause google is my friend and he would never lie to me. Would he?
Or you could disregard all of that and play BC:Rearmed which was mentioned by a previous poster. If your one of those gamers that has a tendency to never give up and you sometimes wonder if you suffer from OCD than i dare you to enter the challenge rooms. You won't like it but at the same time you will. You'll get so frustrated you'll want to rip your own face off.
