To LFO: Interesting suggestion, and I suppose that it all depends on how many tracks you have in your project. For me, I've had up to 30 tracks of audio, and some of those "tracks" were just little fills on guitar or keyboard. I simply couldn't lose all the hard drive space that leaving all the "unwanted" parts in the song would allow. However, if there aren't that many tracks to begin with, this shouldn't be an issue at all. Additionally, I should have also added that I also leave a little bit of space on the tail-end of the clip, just to add a quick volume fade down to avoid any little clicking that might happen (which is almost always the case) at the end of the clip. Are you finding that there are other noise issues besides this?
K-dub, don't joke! I sincerely believe that Nine Inch Nails did just what you suggested for about 2/3rds of their entire music catalog (and I love 'em).
And as for Rick's most recent question, here's where it starts getting both tricky and dangerous (to your audio), and there are a variety of answers. My first observation is that you probably aren't going to any great sound out of your PC speakers to begin with, so that's a hard reference point to work from. From here, it depends on what plug-ins/programs you have to work with. Generally, using a limiter will boost the levels of your recording, but you have to be careful not to damage the audio during this process. Maybe if you posted up a clip of your stuff, and/or told us what plug-ins you use, I could give you more meaningful feedback.