Elrushbo, I hope you have a great time while you're here in Chicago!
This recent thread discusses Indian restaurants, including several that are downtown or near north:
http://www.lthforum.com/bb/viewtopic.php?t=7430
Although I haven't eaten there, people seem to agree that India House is a great place. But if you both really enjoy Indian food, I'd suggest you take a trip up to Devon Ave., which is where the highest concentration of Indian restaurants in Chicago are located. You'll probably pay about $15 for a cab (each way), but I suspect you'll pay less for your meal, regardless of where you decide to eat. I've previously lived in the Middle East, and when I get to Devon Ave., I feel as if I've been transported to Asia...different smells, different sounds, different languages. If you took a picture looking down the street that showed the store's signs, I suspect a lot of frequent travelers would guess there were in another country. So in addition to eating dinner, you could wander into a few grocery stores, there are jewerly shops that sell 18K to 24K gold, you'll see places selling nothing but saris. It's a lot of fun.