Which video card for a small PC with a crappy power supply ?

I got a Lenovo H430 5311430 desktop PC. It has an i5 3330 processor. It's brand new in the box, waiting for Xmas day. (it's a present for the family). I have my own gaming PC in my man-cave that I use, but I'd also like to be able to play games on this PC. So, I definitely need to get a video card for this thing, but I have three major issues to deal with:


Issue No.1 - Power Supply is likely very crappy. (box is still sealed cause it's an Xmas present, but I'll open it up and try to get the exact make and model of the power supply, but lets just assume it's a crappy 300 watt PSU. I need one of those cards that use very little power, so that I might be able to avoid a PSU upgrade.

Issue No.2 - The tower is a small tower. It's not a full sized tower. I'm not sure how much actual room is in there for adding a video card, but I'd imagine that I would need one of those cards that can fit into a small space

Issue No.3 - My budget for this card is about $120 out the door after all taxes, shipping and rebates, etc, etc. I'd really like it to be $99 out the door, but I know that it can be hard to squeeze the price in under that $100 cutoff.