John, we are all a bit gun shy about copyright violations here, so forgive us if you felt jumped on. Technically, replacing one song you bought with another song you didn't buy, "could" get you in trouble if someone wanted to prove you were doing this. You should never had a song on your hard drive (for more than one night at least) that you did not pay for. Microstudio does allow playing from the Singer's disc, so be happy with your song, play theirs for them, and go out and buy an original of their disc and import it legally. Then, you've got the old and the new songs.
As to your not being able to install with the Floppy disc, the only thing I can think of is we use HTTPS (secured) to communicate with the web site to protect your privacy. Some Internet Service Providers have problems with an HTTPS transmission. You may need to enable it to work in your Browser or with your ISP. Call them. If you have AOL... this has been reported as a problem.
If you want to upgrade your Laptop to a USB 2.0 port, be careful! Some USB PCIMCIA cards are terrible and cause no end to grief. If you want to go this route, post here and we'll try to find the offending cards for you to stay clear of.