Excessive noise with no input

Audacity ver 2.0.1
win xp 2.8ghz processor
using realtek high definition audio internal

With no input, the input bar shows about -30db of random noise. I have the windows and realtek sliders set to 3/4 of maximum. I can record and playback the noise. I was doing some LP to MP3 recording and when I played back, it was noisy. Is this computer sound processor doing this? (any other cause?)
I was thinking I need to add a low noise sound card to fix this. Any recomendations as to model number (limited budget)? The hiss clean up function seems to be a mixed blessing, as it apparently can screw up the music. Maybe I am wrong there…

Audacity ver 2.0.1
Win XP 2.8ghz
Realtek internal HD sound

A basic question here: using the line level input on my computer and a line level source, the Audacity input level meter jams full right. I have to drop the gain slider almost all the way down to get it to back off.
Am I supposed to use the Realtek mixer panel level pot to correct this? Right now, I use attenuators in the line cables to correct this. The Realtek sliders were locked (I think due to some Windows update) but now they seem to work.

I’ve merged your two topics as we can probably deal with both issues together,

On-board sound cards are usually poor quality for recording.
What sort of turntable are you using?

a Technics SL 1300

The signal that comes directly from the cartridge of a turntable is a very tiny signal that requires a lot of amplification and also requires special equalization (RIAA) for it to sound right. Some turntables have a built in “phono pre-amp” to take care of both the amplification and the equalization - the audio output from these may be marked “Line out” or similar. Other turntables do not have a built in pre-amp and require an external phono pre-amp.

I think that the Technics SL 1300 does not have a built in pre-amp (but please check your user manual as I’m only going on the limited information from a 2 minute look on Google).

If the turntable does not have a phono pre-amp built in, then you can get USB sound cards that have built in phono pre-amps. Behringer, ART and several other companies sell inexpensive USB sound cards with a built in phono pre-amp. (The Behringer one is a “U-PHONO UFO202” and costs about $35 US.)

I run the turntable through the phono input on my reciever and use one of the line outputs to run to the computer. The noise seems to be generated by the internal sound processor. I am looking for a recommendation for a good sound card now. M Audio 192 is one, but it may be going obsolete.

In that case you just need stereo line in.
I use a Behringer UCA 202 (about $30 US) - it’s no-frills, just stereo line in, line out and headphone out. It’s only a cheap plastic box, but sturdy enough as long as you don’t tread on it and the sound quality is great. It has no input level controls so it is important that the input level does not exceed “line level” (you may be able to control that from your amp).
Alternatively, many of the USB interfaces that have phono pre-amps built in can be switched to line level, which would give you the choice to either go via you amp or direct into the interface.

I fixed all my problems. I got an ASUS essence STX sound card. My no input noise level is undetectable now and the full line input is fully controllable with the sliders. I eliminated the attenuators. The on board sound processor was adding a huge amount of noise.