When you get there you'll see the bloody great statue shown on the first link. The Museum is at the base of the statue. Theres an open air vehicle park with 50+ AFV's in it, WWII and modern, and some arty and aircraft. There is,or was 10 years back when I was there, also an armoured train with JSII turret on it. I didn't go into the indoor section of the Museum.
http://www.armyradio.co.uk/publish/Ukrainian_Expedition/Military_Museum.htm
This link show you how to find it. Its close to the Perchevsky Lavra which is a major tourist destination and well within walking distance of the city centre.
http://www.relc.com/kiev/index.htm