First of all, welcome to the forum
On Napster, regardless of the subscription you choose, the 99c tracks you pay for individually all function the same: You can transfer them to a WMA DRM compliant player or burn them to CD. If your MP3 player supports WMA DRM, it will mention this somewhere on it or within the manual. These tracks also do not expire, however you will have to be careful to keep a backup of your Windows Media Player licenses in case of a hard drive failure. To do this after you purchase and download music, go into the 'Tools' menu within Windows Media player (click the 'drop-down' arrow at the top-right of the window), click 'Tools' and select 'Manage Licenses...'. Click 'Back Up Now' and follow the on-screen steps.
WMA is a lossy compression, which means that when the audio is compressed from a CD Quality source, some audio information supposedly in-audible to the human ear is thrown away. The purpose of this is to reduce the file size by a factor of about 10. For example, a typical 4 minute CD Quality track would take up about 40MB, where as the same 4 minute track compressed in WMA or MP3 at 128kbps (the bitrate most music services use) would take up about 3.8MB.
If you are well familiar with the sound quality of MP3, but have not tried WMA yet, your likely first impression will be that WMA sounds better, since WMA does not have the same audio compression artefacts as MP3. However, once you listen to WMA for a while at 128kbps or lower, you'll soon start noticing the artefacts caused by the compression. In my opinion, WMA sounds worse than MP3, however I know people who say the other way around. It all depends on how annoying you find the audible artefacts and that's if you notice them.
Napster uses 128kbps encoding from what I recall for all its music, whether purchased as permanent downloads or as part of its unlimited subscription service. The best way to get an idea of what Napster's music will sound like is to try compressing a CD in Windows Media player at 128kbps. To do this, click the drop-down arrow to the top right of the Windows Media Player window, click 'Tools' and select 'Options...'. Go to the 'Rip Music' tab and drag the 'Audio quality:' slider until it shows "(128 kbps)" (if this is not already chosen) and click 'OK'. Click the 'Rip' tab and insert a music CD to rip into Windows Media Player. When the player rips the music, it compresses this into WMA; the same audio codec Napster uses. Finally, go into the 'Library' tab to play the music you've ripped and use a good pair of headphones to see what you think. :rolleyes:
If you are not happy with the sound quality of WMA, then unfortunately Napster would not be suitable for your needs. iTunes uses MP4, which has been tested to be better quality than both WMA and MP3 during blind audio tests. Unfortunately, the majarity of music services use the WMA format.
Unfortunately, the only streaming radio services that work well over a modem would be services that stream at 32kbps or lower. A 56k modem only effectively transmits data at between 32kbps and 40kbps. The best way to check your effective transfer rate is to try downloading any item and monitoring your transfer rate. Multiply this by 8 to get your speed in kilobits. For example, if you get a speed of 4.5KB/sec, then this works out at 36kbps, which would be the maximum streaming speed your modem can handle. BT Openworld provides several 5MB to 15MB dummy files to test one's transfer rate, which can be accessed at http://www.btopenworld.co.uk/speedtest