Looking to get Deus Ex HR but looking from reviews it's heavy on CPUs but a little easy on GPUs unless your using DirectX9 (I would be as my GPU does not support DX11) which has worse performance then DirectX11 which I thought was kind of odd. But I'm wondering if a Phenom II X2 @ 3.7GHz could handle this game at 50+fps or at least 40+.
If you have a mid range graphics card or better, and you don't game over the resolution your card can keep up with (1680x1050? 1920x1080?), you should be fine. DE:HR is a great gaming experience if you like that type of game. I have it and the DLC for the game. I highly recommend it. What is your PH II X2? It sounds like it's overclocked.
LOL... I guess I have to learn to look down and read the signature too. Sorry. Been a long day...
I would guess you are right at the limit for 1920x1080 with full eye candy w/GTX 260 and a dual core. But the CPU being OC'd I would think it would still be a good gaming experience. DE:HR doesn't use cutting edge graphics, so you can back off if necessary and still not loose the beauty of the game.
I had a 2nd machine that had an Athlon II x3 @ 3.2GHZ and a HD 5770 (about the same league as your GTX 260). While I only played it on a 1680x1050 display, I had all the settings maxed out with no issues. I never checked framerate, but there was no noticable lag or stutter. I realize your resolution is higher, but I wouldn't let that keep me from enjoying a really well made PC game that for once isn't a console port.
And, yes, you probably need to stay at DX9. DX10 had issues that slow down performance.