First of all, my friend, You are talking about during the holiday of Hanukkah right? If not correct me.
If you tipe Hanukkah into google images you will get approximately the same amount of Hanukkah Menorah's as the number of trees you will get if you tipe Christmas in the same place. In fact there is only 1 nativity scene on the first 3 pages of photos (and one photo of 3 really hot anime girls dressed in minimal clothing).
In the lobby's of most guarded, or modern, buildings in New York you will find a tree and next to it the Hanukkah Menorah. This is because of the lighting of the candles during every day of the holiday, rather than representing the Jewish religion (It is not smart to light a Menorah next to a tree inside a building).
Now that I think of it, I understand that many people mistake the Hanukkah Menorah, or Hanukkiya and the Temple Menorah, which represents the Jewish religion, to be the same thing, but they are not. They are two completely different symbols. The temple Monorah is a 7-branched candelabrum with a very distinct shape and adornments, representing the Jewish religion, while the Hanukkiya is a 9-branched candelabrum, which is strictly used in Hanukkah to represent the 8 days of the holiday (along with the Shamash which is the 9th candle-stick used to light the other 8).
As for how the tree has anything to do with Christianity:
According to Christian lore, the Christmas tree is associated with St Boniface and the German town of Geismar. Sometime in St Boniface's lifetime (c. 672-754) he cut down the tree of Thor in order to disprove the legitimacy of the Norse gods to the local German tribe. St. Boniface saw a fir tree growing in the roots of the old oak. Taking this as a sign of the Christian faith, he said "...let Christ be at the center of your households..." using the fir tree as a symbol of Christianity.
The tradition of the Christmas tree as it is today known is fairly young. It was established by Martin Luther as a Protestant counterpart to the Catholic Nativity scene. Luther established the Christmas tree as a symbol of the Tree of Life in the Garden of Eden.
It seems the ACLU is having Chatholic vs. Protestant problems rather than Christian vs. Jewish and Muslim problems.
As for what I personally think about it, and not only me, but the constitution of the United States. It is that the first amendment of the constitution clearly says, "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."
It means congress will not establish a state religion, or create its own religion. It will not favour one religion over another, non-religion over religion, or religion over non-religion. It also means congress will not prohibit the free exercise of any religion.
In my opinion, and the opinion of the constitution, Christmas, being a Christian holiday may be practiced and exercised freely be it through nativity scenes or trees.