Well to me this static has just as much to do with your power source and power outputs. So you are using line in capable sound card that is almost the same as using a mixer station/interface. I am confused as to whether

I am attempting to record a guitar and a mic through direct input to my pc

meaning you have a guitar amp that has a mic on the speaker. Or are you saying that you have a guitar plug straight into the sound card and a mic separate for like vocals.

The main thing here is that we need to know whether the amp is making a hum or that there might be a ground loop problem in your setup. If you are plugging in a single coil guitar there is always the presence of ground hum that comes with that setup. Lets stop there and find out how you are plugging your guitar into your system... Either directly in or into an amp that mics the output into the sound card. There is a big difference in the answer to what you might need to improve your sound.

Sorry I should have been more specific. I am plugging my guitar as well as a seperate mic both directly into the stereo input on my PC. (left for guitar right for the mic) I am not using any kind of amps or preamps or anything. I believe the moise is mostly (if not completely) within the PC because even when I plugged in my ipod to the input i could hear a bit of static during quiter parts (but not when i played music from itunes on that pc). Also when i had my guitar plugged in with a vst amp and the guitar's volume lnob at 0 there was still quite a bit of background noise. I just wanted to know if a usb audio interface would likely be a solution to this problem. Thank you.

Since the static is present from multiple devices (guitar or ipod) it seems to be the power switching capability of a computer power supply might be your culprit. Now that can call for a ground lift on one device to prevent ground loops. However, it might be something where if you add an interface this will help drastically bring down the ground noise (static) that you are hearing. Another tactic rather than ground lifting, which can be dangerous if done wrong, is to isolate the ground noise by way of an isolation transformer. This helps to reduce ground loop hum that is present on your power outlet, and computers are prone to induce hum in circuitry. Those are usually pretty expensive, so I also did a search for something that you could plug into the wall outlet and then connect to your computer power supply.
This is probably one of many brands of ground loop conditioners and is much cheaper. However, maybe someone on this site will let us both know if a product like this actually works well. You can find this brand at Guitar Center, Sam Ash, or Antique Electronic Supply.
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Edit: I also would like to recommend a DI Box that you plug your guitar into to change from high impedance to lower impedance levels. This will help your signal chain for recording straight into the computer sound card. Although you really gain more by having at least an interface that will accept the XLR inputs. The DI box can take your unbalance signal and convert it to a balanced signal. This will greatly increase the sound quality of your guitar recordings and the DI will have a ground lift switch on it that will then help if you use single coil pickups or what have you. Go read about those and find one that you can afford. Ask questions as you do this and someone here will definitely help you along the way. Good luck!