If your soundcard has ¼’’ jacks you are ready to go, if the soundcard does not have them; then, all you need is a conversion jack. (¼’’ to 1/8’’)
This is not the ideal way of recording; but it will allow you to take the signal from your guitar to your computer.
The best way is using an USB or FireWire interface. (I recommend FireWire)
The guitar has a high impedance signal and you need a way to convert it to low impedance, many devices do the trick such as direct In box, (DI) preamps, sound interfaces, mixers and multi-effects units.
So, if you connect your guitar straight into your soundcard the sound is going to be kind of flat and lifeless,
fortunately the sound interface can convert the impedance to give you a better sound quality and allow you to monitor what is going in and what is coming out your computer.
As Superhuman said, make sure the interface has enough In and Out jacks to suit your needs and near zero latency.
The only 64 bit FireWire unit I was able to found was a rack-mount Mackie, but it is also used as computer interface.
http://www.amazon.com/Mackie-Onyx-400F-Rackmount-Interface/dp/B000CR4NV8
From Amazon.com
Onboard 10 x 10 Matrix Mixer with 64-Bit Processing
The Onyx 400F is the first FireWire audio interface with a true 64-bit onboard Matrix Mixer with floating-point DSP. The DSP-controlled mixer lets you route any input to any output with panning, level control, mute and solo controls, storing your mixes for instant recall. And it operates with or without a computer. So you can, for example, make five custom mixes of incoming live inputs, plus two channels coming back from your computer—patch in external compressors or reverbs—and send individual near-zero-latency stereo headphone mixes to up to four musicians, with an extra independent digital mix to your DAT or CD recorder.
Hope that helps. :)
