2007 2.5L serpentine belt replacement
If anyone cares ..... I replaced the serpentine belt on my 2007 2.5L 4-cylinder Altima last night and it was quite easy. I was anticipating bloody knuckles, etc. as the space looked pretty constrained when I looked in the engine bay. However, you pretty much access everything from below [rather than from the top] and there was plenty of work space.
I removed the right front wheel and the wheel well cover, and had access to everything needed. I used a 14mm combo wrench to rotate the tension adjuster, and used a 1/4-inch hex bolt [inserted in the boss] to hold the tension while removing/installing the belt. I was laying on the ground when I rotated the tensioner with my right hand, and was able to insert the bolt with my left hand.
It took less than an hour, and I had to play with my son for part of that time too. This was the original Nissan belt with 87k miles on it. I went with an aftermarket Gates brand belt [not Nissan] just because I was driving by the parts store at the time.
If you change your own oil, you should be able to do this task as well.
2007 Altima 2.5SL