Hi i seek your advise to upgrade my PC.
Its an oldie, but i hope we can still use some of the parts.
I currently use it for just games like World of warcraft, diablo 3,but i like to Fraps or stream my sessions. Besides thats is mostly for office use, browsing and stuff.
Currently i get like 30 FPS and i feel it pretty slow if have have other apps opened.
This is the configuration i currently have
Proc: Intel Core 2 Duo E8400 Wolfdale 3.0GHz
Fan: Cooler Master V8 CPU Fan
Mem: mushkin 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800
Video: NVidia Gforce GTX285
HD: WD 1TB 7.2K SATA 3.0Gb/s
PS: Corsair CMPSU-750TX 750-Watt TX
OS: windows 7 Ultimate 64bit
Mon: 22" WS Viewsonic
Case: Cooler Master HAF
Your GTX285 is on the same tier as the HD7770, and weaker than a GTX650Ti. Your saying it slows down when you have other applications open points to a CPU or RAM limitation though. With only 4GB of RAM, adding more may make a difference, BUT you're limited to DDR2, which is getting more expensive and can't be re-used. If it doesn't help, you've wasted your money.
While a stronger graphics card may help in some circumstances, I don't think that's where your problem is. Capturing or streaming your sessions is CPU-intensive. Your older dual-core may be struggling. Have you tried overclocking it? 3.4GHz should be attainable; does that make a visible difference?
I hesitate to make upgrade suggestions without knowing your budget. You certainly have some reusable parts, like your PSU, case, and drives, but a substantial rebuild with a quad-core CPU is a minimum of $300 (CPU+mobo+RAM), and more likely closer to $500 especially if you need a new OS license.
OTOH, if your budget is very limited, adding 4GB of RAM and overclocking your CPU is your cheapest option. Before buying anything, OC the CPU to see how much difference it makes. Decide from there.
Ah, with a $500 budget, then take batuchka's advise, but feel free to not initially upgrade your graphics card until you see what you get with the new system. At only 1680x1050, what you have may have some life left in it. Better to spend the money on the core "infrastructure" of your system; graphics cards are easy to upgrade later.
How old is your HDD? I see it is SATA 3Gb/s; if it is five years old or older, you may wish to replace it if only because it may be nearing the end of its useful life.
If you get a SSD, you won't see any improvement in FPS, but your entire "user-experience" will improve. Right now, the 128GB Crucial M4 is $120: http://www.newegg.com/Product/Product.aspx?Item=N82E168... with free shipping. That's probably the one I'd get.