OK, first off, if you havent done it already, download Windows Media Encoder 7. For these tutorials I figure itll be easier to use a bulleted list.
Open Windows Media Encoder 7.
Select "Broadcast, Capture, or Convert a file". Click OK.
Select "Convert an audio or video file into a Windows Media file". Click Next.
Select the AVI you exported from Premiere or Quicktime Pro. Click Next.
Select "File will stream from a Web server or play directly on a computer". Click Next.
Select "Video for broadband NTSC (256kbps)". Click Next.
Input whatever information you'd like here. When you're done, click Next.
Check the settings and make sure everything is as you'd like it. Click Finish.
Click "Start"
An ASF/WMV version of your video should now be in the same directory as the AVI. View it and make sure you're satisfied with it. (Note: There WILL quality loss, no matter what you do. Its the price you pay for having it be a smaller file.)