As Dee-ehn said, if you want your "compressed CD" to be a "regular" Audio CD, then there is no hope to do it. This is because the audio format for CD audio is fixed, that is stereo, 16bit samples at 44100 Hz sampling rate.
If you are not interested in compatibility with the CD audio format, then you have several options that allow you to build a data CD with your music. From your example of 900meg->800meg it seems that you are thinking about a moderate compression rate. If you want, you can achieve an almost 2:1 ratio (that is, storing about 160 minutes of music on an 80min CD-R) using a lossless compression format. Monkey's Audio and FLAC are two examples. The great thing about lossless compression is that there is absolutely NO loss of audio quality involved in the compression. If you decompress the audio file, you will get the original file, bit-per-bit identical. And of course, most lossless formats allow decompression-on-the-fly, which means that you can listen at your compressed CD with software like winamp or foobar2000...
I use lossless audio compression mostly for archiving purposes.
Hope this helps,