My Asus Pro5Di Duo T3300, 2gb RAM, 320hd copes with Mir easily and good for other progs etc. It's on Win 7 Pro, not Win8. I even ran Lineage 2 on it but its not really playable.
If screen size is an issue then maybe this won't be for you, it's only a 15.8in widescreen display.
It's a few years old now and 2gb ram probably a bit low nowadays but if you find this or newer versions, you can't go far wrong.
I got it from Misco for £200+vat lol.
Have a look at Asus. Their after sales support is good too.