Windows first. That good old standby vinegar and water works great. I use 1/4 C. white vinegar and 2 C. water in a spray bottle. Mirrors, glass and chrome come out streak-free and clean. There are a lot of wonderful household cleaners that you can easily make yourself with common ingredients. To get some good recipes visit Women's Voices for the Earth. You'll find recipes for all-purpose cleaner, drain opener, and more.
Weeds are a little more difficult. There was a study done by the University of Wisconsin-Madison Department of Horticulture that showed that vinegar (acetic acid) works well as a weed killer. But what worked the best was a 20% solution (the stuff we buy for home use is typically only 5%) which is not easy to purchase for household use. I have successfully used vinegar mixed with liquid soap and water as a weed killer but only in areas such as a brick path because the spray will affect almost any plant that it touches. A single application will kill the plant; the exception seems to be plants with fuzzy leaves, for some reason they are not as affected by the solution. Plants with thick roots, like dandelions, usually have regrowth, however multiple applications appear to weaken the plant and, in some cases, completely kill it. I use a formula of 1 part dish soap, 2 parts vinegar, 2 parts water. So for a small batch you would make up a solution of 1/2 C. dish soap, 1 C. vinegar and 1 C. water.
It's a good thing to be able to use ingredients that do the job without relying on harsh chemicals that aren't good for you or for the environment.