When you say untreated room, do you mean void of furniture/bookcases/wallhangings? Somewhere, possibly on this website, I read that if you hear an echo when you clap in the middle of the room, it's not "flat" for recording. I walked around my house, room to room, and found that the most "flat" rooms were the study (even though there are 2 very large windows in the room) and our master bedroom, which has an 8'x5' window and 2 doors. The study was good because of the wood cabinetry on pretty much every wall, with bookcases. I was surprised to find that our room was almost as flat, and dramatically improved when I put blankets over the doors and closed the blinds. I figured if I shut out light that was coming in through the cracks at the top & bottom of the doors, it would help, and it worked!
I'm happy with my condenser mic in this setting - I have to have the ceiling fan turned off because it registers in my DAW! The condenser mic we use is an MXL V63M we purchased at Musician's Friend for under $100, and it came with the shock mount and a cable. Definitely get a metal pop filter with whatever you decide to purchase. When you use a condenser mic, you really need the filter, because the diaphragm is so sensitive. I used dynamics for years for recording, but condenser (even a cheap one!) is really the way to go.
There are some great threads on this website that explain the differences between dynamic and condenser, but the very best place to go, to get an understanding of why you want to invest any money in condenser mic's, and how they work is HARVEY GERST'S MIC LESSON. It's a lot of info, but very interesting and educational.
