With regards to your questions about the speaker volume, you may want to do the following:
1) Check the connection between the speakers and the PC. Are they secure? If not, secrue them.
2) Also check if within the Windows environment - whether you've enabled the sound to maximum. Sometimes you need to up the master volume and also the WAV file volume.
3) The other thing to do is to try the speakers with a normal Hi-Fi or another computer. Do you get the same problem? If you do, then its the speakers that are defective. If not, then the Dell has a problem. You may want to get an additional sound card to help matters.