funkifized:

After you've checked out the videos (as per Noel's advice above), here are a couple of things I've found, that hopefully will give you something to think about for your stated questions.

- you said you "want to add my own guitar to tracks that sound decent". To what does "decent" refer? To YOUR guitar tracks or to RealTracks? <grin> If you want to check out RealTracks you can "mouse around" the PGMusic website and find demos of each that you can listen to. Then you'll know whether they are "decent" (if that is indeed your question).

- the interface you will need, depends on how you want to record your guitar. You say you want to go from your effects pedal "into the soundcard input".

What soundcard are you using?
If you're just going into the "Mic In" or "Line In" on a PC or laptop that doesn't have a dedicated "soundcard", you may or may not be happy with the guitar recording you get.
You could try it this way by just recording into (say) Audacity (freeware) and see if you like the guitar sound there.

If you don't get the sound you want that way, you may have to get a pre-amp or perhaps a small mixer to route your effects pedal to the PC.

The other consideration is, if you don't have a dedicated soundcard (e.g. Audiophile 2496 or some such), you may not get the quality of sound you're after no matter what you do. I'm assuming that although your effects pedal is "digital modeling", it still puts out an analog signal which must be changed to digital in order for RealBand to use it.

That means that somewhere in the signal path, you need a good (or at least adequate) A to D converter. A "soundcard on a chip" might not be enough if that's all you're using.

Let us know more about your setup and perhaps someone more versed on the subject can get you some help.

Good Luck!
LLOYD S