The only Russian insults I remember are "cheerka", which means "block of wood" and is a way of calling someone stupid and "zhopomordyi", which means "ass face." These probably are not a good way for you to maintain the moral high ground.
My russian customer service person says to pronounce it "churka" and it means a roob or something like that. She also told me that "sooka" is bitch, "blyad" is c**t or similar. She says that all the time too! Man. Glad its not at me. LOL
Get your company to relocate you and the insulting coworker to Georgia. You can apparently still commit an act of simple battery if provoked by his "fightin'" words. Source: http://www.fun-facts.com/fact-183.html?sort=date (originally dumblaws.com, but I can't find it there any more.) So move and give that boy a countryfied ass-whoopin'!