Okay- I just realized I can add a picture this way.....

What makes the most sense to me as far as the furniture arrangement goes is to center the loveseat on the wall where the piano currently is, then place the tv on a low console on the wall where the loveseat currently is and the piano would go on the wall opposite the windows. This allows the seating to be directly across from the tv for comfortable tv viewing and hides the tv so it's not seen from the entryway. You could then add new paint, end tables with lamps on either side of the loveseat to visually extend the focal wall (nearly always the wall with the sofa when there's no fireplace). Hang a piece of fresh, updated artwork over the sofa and a pair of drapery panels at each window and possibly add an occasional chair to form a real seating group and this will feel like a whole new room.

If that is actually a return air vent and not a supply vent, there is no reason the piano can't go on the wall where the love seat is now. Just hold the piano out 2 - 3 inches from the wall and you'll have plenty of air movement. That opens up other arrangement possibilities for you. If it's a supply vent, I agree you don't want the heat blowing directly on the piano.

I agree with dlm that the piano should go where the sofa is, and an intake vent shouldn't be a problem.
I wouldn't want a TV between 2 windows since daylight coming thru would run me crazy while watching TV before dark. If the room is large enough, what about putting the sofa in front of the windows, with the TV on the opposite wall?

For now (until the corner armoire is removed):

1)Place the loveseat in front of the windows. Leave the area rug in front of the loveseat.

2)Move the piano along the LONG wall of the corner (to the LEFT of where the loveseat sits now in the 2nd photo)

3)Add a comfy chair to the short wall where the loveseat now sits.

4)Add the artwork above the piano ....

Thank you for all of your suggestions. The love seat will not work between the windows because that space is only 49" wide and there are plantation shutters on the windows that are frequently opened. I would love to have the piano on the wall where the love seat is now but we have to have access to the intake vent to change the filters. It would be difficult to move the piano each time and would likely damage the floor.
That is a good point that Annz makes about the light coming in the windows and making it difficult to see the tv.
I also forgot to add that I want to increase seating in this room. Ideally with the love seat and two comfy chairs with a movable ottoman. I'd get rid of the coffee table.
I may be asking to much though of this little awkward room. It's what you see when you come in the house and I really want a beautiful, inviting space.

If you try the layout I suggested, you could be sure to get a tv console on wheels to easily move it out to access the vent. I don't see why you couldn't do 2 small scale occasional chairs in front of the windows with a small round side table between them. Just be sure to consider the scale of the room when shopping for them.

Because the room is small I'd play around with the layouts either on the computer or with scale cut outs on paper. I think Pegasus has a good direction to start with, I like the idea of looking in and not seeing the tv.

Ok- I've made the room and cut outs to scale as suggested by gmp3. Here is my question. Has anyone ever seen a large screen tv hung above a piano??? Would that just be terrible? I think I know the answer to my own question but we are hitting a total block with getting what we want out of this space.

I would get rid of the shutters and do something else on the windows. With that small space you really need to be able to use that wall with the windows.