Normalizing is a process of adjusting the volume of an entire track such that its peak (loudest point) is at or below a specified level (typically at or just under 0db). If the overall level of your track is low, the typical "normalize" routine of your software will bring the level up as high as it can without any portions crossing the "redline" threshold. Therefore your track, in itself, will be as loud as it can be without distorting.
You probably know that raising the level of a track will also raise the noise level in proportion, because the noise is PART of the track. Now, depending on the dynamics of the track, bringing the level up might make the hissing appear to be less because your ears can focus better on the music, but in reality it is just as loud. And that sucks.
There are two ways to eliminate noise as I'm aware of (and I'm not the brightest cookie around here). The first way is to run a noise filter or gate. A filter, as I'm aware, will extract unwanted frequencies from a track (e.g. noise) which is usefull if you've got a pretty constant noise source, but otherwise it can and will damage the rest of the track and should be used with caution. A gate, on the other hand, simply sets the volume of the track to nill whenever the level reaches a specified low point. This is usefull for, say, a quiet hiss behind a powerfull guitar track. While the guitar is playing, you don't notice the hiss...when the guitar stops (or comes close to it), the gate trips and the volume is set to nill. But you guessed it, this doesn't help when you've got a track with a fair amount of noise.
The second way to eliminate noise is to not record it. This is the BEST way, and the only REAL way. People will often refer to the "Signal to Noise Ratio" when talking about shit like this. Basically S:N is the amount of good signal vs. the amount of noise. The more signal you have, the less noise. Remember when you'd record with your old tape deck, and you'd adjust the Record Level until the meters would be up in the yellow? You were getting as much signal onto the tape as possible, and thereby reducing noise, even if you didn't know it!
This same principal holds true when you're recording with a computer. Most if not all soundcards have an adjustable Line Input level that you can manipulate via the Recording Control in Windows. To view the Recording Control, double click the little speaker icon that sits on your taskbar. The Volume Control will come up. Now click Options and select Properties, then tap the Recording radio button and make sure that Line In is checked in the box of controls beneath. Now click Ok, you'll see the recording control pop up. In my opinion, it is best to set this level at about 75% and just leave it there. If it's too high, you'll be turning your sources down too low. If it's too low, you'll record too much noise from the card. If you want to adjust it every single time you record something, be my guest, but I think it's a pain!!!!
Now that that's taken care of, you need to fire up your recording software. I don't use Cool Edit, but there should be a Recording VU meter somewhere that works just like the VU meters on your tape deck. Start playing your source and watch the meters. Cue the source to what you think is the loudest part of the track, and adjust its output level such that the meters (in Cool Edit) never go above 0db. In fact, you might set it such that the meters never go above say -2db to -3db just to be safe.
Now you're ready to record. When you're done recording, make sure that there weren't any questionable peaks (e.g. above 0db). At this point you want to normalize, though it's probably not necessary if you did a good job setting the levels in the first place.
If it's still hissy after this, then the issue is your soundcard. Your soundcard is basically a glorified Analog to Digital converter that converts analog input into 1's and 0's for the computer. Unfortunately, good AD converters (and vice versa, DA converters which convert digital to analog) are not cheap. Cheap converters are inaccurate and highly susceptable to noise (interference). "Inaccurate" will result in a poor sound, perhaps "tin-ny" as you described. "Noise" is of course that nasty hissing we're trying to get rid of. Combine the two, and we've got exactly what you're describing.
You may wish to check the "noise floor" of your soundcard. Without any signal coming into the card, what do your VU meters read? If they read above -40db, then your card is very noisy. If they read between -60db and -40db, you're kinda in the "ok but this sucks" range. A decent card will not produce enough noise to register on most meters (less than -72db).
If you decide that your soundcard sucks, you might be SOL because you've got an HP. Pavillions especially are notoriously poor upgraders.
If you try to upgrade, your best purchase will be an Ensoniq AudioPCI or a Soundblaster PCI128. Both of these cards are very quiet and are adequate for recording. I use an AudioPCI myself, and am happy with it for now. Both of these cards should sell for under $30 at most retail stores (Staples, etc). Online you can find one for perhaps $20. Not a bad price.
If you're wondering why the hell I'm being so damn longwinded with this, it's because I have 8 more minutes before I can go home, and I stopped working about 20 minutes ago. Therefore, I'm just killing time and this seemed like a good way to do it. So...blah blah blah blah blah.
In regards to sample rate, you're not using 4800hz, you're using either 48,000hz (48Khz) or 44,100hz (44.1Khz). 44.1Khz adheres to the CD audio standard. 48Khz is a teaser to make you think that your card is somehow better than cards that can only do 44.1khz. Most audio applications default to 44.1/16 and you have to manually adjust to 48Khz. If you're going to be running any DSP (digital signal processing, e.g. effects) on your audio, it's always recommended that you start with the highest sample rate and bit depth possible when recording. But note that to burn CD's, you'll have to dither down to 44.1/16.
Since you're not going to do a lot of manipulation in this case, I'd recommend saving the hassle and just recording at 44.1Khz.
Ha ha, 8 minutes is up. I'm outta here. Good luck.
Slackmaster 2000
Technicalities...blah!