Yeah, its possible. However, the smaller you go, the lower the quality.
Still, its really easy. Go to : File > Export > Adobe Media Encoder. Once there, you can select which type of output you want (I.E. WMP 9 1024 KB Download, or even 256 KB DL.) For my website, I usually compress the videos to 256kb dl, to make it smaller.
You can fiddle around with the settings to see which one works best.. but beware.. it does take about 5-15 min for around a 5 min video.
Hope that helps!!