It's not supposed to work that way - it's a USB device and replaces the sound card - if you're going in via the line-in socket, I'm guessing you're using the headphone output on the Behringer via the original sound card - hence the latency.

You should only have to plug the Behringer into a convenient USB socket, plug the guitar into the Behringer, then select the recording device from the volume icon in the task bar... no latency!

It may take a bit of trial and error, especially to be able to hear the output through your computer speakers - plugging the speakers into the headphone socket would be a workaround until you get it right.

If you're still having trouble you could ring me and I'll try to talk you through it - you'll find my phone number on Lymm Folk Club's website!