>1) since the video is large i want to find out how i can further compress it (if possible)
I'm assuming you have Quicktime Pro. (If not, get it online. You can pay for a fast cable connection...) You can open the video in Quicktime and use a wide variety of compression settings.
Depending on what you plan to do with it, you should use different settings. If you plan to use it on your computer in the quality of, say, a premium music video, as well as MPEG-4 video, go to Export, select 320 x 240 pixel video (you can also use 400 x 300 and select no compatibility options in the last tab), choose 29.97 fps (if you really want to cut down, you can use 15 fps, as dukestreet mentioned), around 128Kbps audio, and, if you plan to stream, ample stream settings. Also, use about between 700 and 1200Kbps video output. If you are unsure of what to use, choose 1024Kbps.
If you want to use a much higher quality scene, for presentations or for HDTVs and iDVD, you might want to leave it as it is and export to a DVD-R.
2) i want to be able to convert to be viewed by real player (if possible)
It is possible. Export your movie through Quicktime Pro and select Movie to Toast Video CD (don't worry about the title, the extension and file type are MPEG-1, which works for Realplayer). If you are planning to use around a 320 x 240 res. select between 1536 and 2048Kbps for your video quality. Your audio quality should also be around 128Kbps, if not, greater, since compression will be less with MPEG-1.
3) i want to be able to convert it to be viewed by windows media (if possible)
Again, in your Quicktime Pro export settings, choose "Movie to AVI" from the first pop-up you see, and apply ample converting options. For the video compressions options, though, you may want to increase the video quality of the Export. If you want to get the best results for the video, select 2048Kbps. Compared to the MPEG-4, though, your file will be between 4 and 10 times larger. If you are willing to sacrifice video settings, do so. The same with audio.