Guitar DI box. Passive or active?

[vonRed]

So, if I plug into the line-in on the soundcard do I use a DI box, or a pre-amp, or both?

You use either

• a preamp designed to handle your guitar's signal

or

• a DI box (active or passive)
• a mic preamp

So, if you've already got a really nice mic preamp you'd like to use, get a DI box. Else get a preamp.