Mirc
Not mIRC!!!
I've always had problems pronouncing Rs any other way than that.
Last year I remember I was still slipping one or two in there in English conversation, though definitely not very often (maybe once ever 2-3 days of speaking in English-only), I'm not sure how I'm doing right now since it's been 3 months since I've been abroad. It's all a matter of what you're used to.
