I run EDH on a 10 year old AMD Athlon 64 X2 6400 (3.21ghz) with Win 10 (It ran better on Win 7) at 3072x1280 resolution eyefinity with an ATI R9 285 (for mixed portrait mode.)
I enjoy perfectly acceptable gameplay with med-high settings between 20 to 60 FPS depending on the environment.
I run vsync with frame rate limiter on 60FPS and its really smooth even with Track IR.
The exceptions are space stations, and a little menu lag in RES'es, but quite playable in a wing.
Planet generation is typically acceptable except for the 2.2 bug that introduced stutter around binary planets.
The biggest setting to watch out for is to keep supersampling at 1.0 or less.
EDH typically uses 65-100% CPU. The highest usage is inside starports, and don't let 4gb RAM worry you. ED, Windows, and all the software to run joysticks, track IR, etc... only uses 65-85% RAM dependant on windows background crap.
Make sure you get minimum 2gb graphics card, more if possible, ED will use it!
The biggest problem you will face with an older system is running background apps, such as EDEngineer, Captain's log, Voice attack etc... I wouldn't get too hooked on 3rd party apps until you can get a better mutitasking machine, ie 4+ cores. I do however run ED Market Connector with no problems. Tabbing out to a browser can sometimes be veeery slow ... (YMMV) I find Firefox to eat up the least resourses while i'm playing.
TLDR It will work. Use med settings, SS 1.0, don't expect to run too many 3rd party apps.