I have been where you are right now ..
I bought an Emachine EL1352 and then got bitten my the gaming bug.
Long story short , I went and bought an NVIDIA lowprofile 440 card thinking I'd be o.k.
I am pretty sure your internals , like the other slimline models , are configured the same as mine from the looks of it.
Do this ; open up your case and look at the PCIe slot for your card.
Is it way at the top of the case?
If so , then bear in mind , it is upside down essentially. The fan/heatsink will not fit.
I solved this buy moving everything into an old case I had laying around. It took quite a bit of creativity due to the very short wires attached to the power supply.
I Also had the 220 WATT psu. I ran the GT440 on it anyway , and ran Skyrim , Crysis2 , and EVE online at max settings.
Later on , I got a deal I couldn't refuse on a 550T TI. I took it home and it fit , although I did have to negotiate with one of my USB ports ( no biggee ) and upgrade my power. The 555 TI needs it's own power cord from the psu , and the 220 we have simply won't work even if it could magically spew out extra wattage.
So if you upgrade your psu , please do yourself a favor and get a modular. That way you can have whatever plug in type you want , when you want it. 600 Watt should suit you fine in my humble opinion.
If you are like me on this , you'll deal with it as best as you can , but never buy a slimline model ever again.
I hope that helps you solve your issue and maybe avoid some of my headaches.
well , back to dinking around on Saints row 3 o/