But can it play Crysis?

I'm guessing it can ;-)
Well, here's a few ideas to get you started: http://www.rage3d.com/board/showthread.php?t=33902850

Funny find... I fired up Batman: AA for the first time with the new processor, the game runs so much faaaaster. On my old CPU, I didn't have stuttering or lag, but it appears that the game just ran SLOWER in general. Everything was fine, smooth, and the talking/action was basically normal speed, but now with the new processor it still is, but faster and the combat is way more hectic, and harder. It's a little hard to describe, it just feels like my old computer couldn't quite handle running at full speed so it slowed it down like 10% or so.

I certainly know the feeling. It's SO good, I actually refuse to play games any less fluid ;P.
It's basically what I would call "hardware overkill":
your minimal framerate = your average framerate = screen refresh

There is always that rush of excitement on your first new PC, I got that when I built my first when I was 10. 2 years ago it was my dual-core 2.5, man that thing blazed through stuff like BF2142 on maxed where my old 2.1 single-core would run on medium and go slow. Great feeling. Then UFO: Afterlight ran on medium without freezing for once. Great.
Last christmas it was my mobo that died, cheap Biostar, so I got an Asus combo with an AMD 2.6 quad-core. Now that was a HUGE boost in speed, got that rush again for every game running maxed. Sadly only ones that don't run maxed are Far Cry 2, Crysis, and Bad Company 2 but that is because I got a $50 9500GT vidcard in my system being my new bottleneck. Anyway keep that feeling of speed as long as possible, makes the PC feel like you built the best damned thing in the world!

Yeah, the first breath of life coming from your home-built machine always feels like a good sensation :-P
On any new system of mine I usually "test" the water with emulation. MAME, in particular, with some demanding 3D game. Fighting Layers (deprecated, my system is too good now), Tekken Tag Tournament etcetera...

So I take it Windows had no problem recognising the CPU? Only I recently upgraded to a Phenom II x4 too and needed to flash the BIOS to get it recognised and working properly.

That sounds like the mobo wasn't properly picking up the CPU, not Windows. I have Windows 7 installed, absolutely 0 issues with anything. My only issue is I might need a bit of extra ventilation/fans, but in regards to software no problems.
I do really really need a new graphics card, planning on picking one up in the next few months, still using an old 8800 which is bottlenecking my system a crazy amount. The 3dmark benchmark I ran gave back really funny results, my CPU scored like 25k, my graphics card like 3k.... I think the range of average was like 8-20k ish for both, so I'm high on one, crap on the other. But games run pretty well still. I have Dragon Age basically maxed out with no issues.

Ive got a low system.
Gigabyte GA-MA780G-UD3H
AMD Phenom II X4 920
Geil Ultra Plus 4096 MB DDR2 1066 MHz
Gigabyte Superb 460W
MSI R4850-2D512-OC-PCIE
Samsung 1TB 7200rpm 32 MB SATA 2

I think thats one of the best things when you upgrade and find out the game runs faster.
On my old system i was used to playing stuff at under 20 fps and it didnt really bother me but now my system can run things so well that under 40 seems sluggish in alot of games.
My computer only has problems running two games. Crysis i can have everything maxed at 1920x1080 and at hectic times it will drop below 30 and KotOR at hectic times will drop below 20.

Crysis has issues no matter what you run it on, it has crappy code on top of intensive processing power

It was a BIOS issue. Hence why I flashed the bugger. But without Windows recognition it won't install the drivers for it. And there's nowhere else to get the drivers from anymore.

It sure beats magic smoke. LOL.

I second that, Crysis seems to be made for magical future-computers that run on pixie dust instead of electricity.