Thanks everyone for your replies. This already relieves my sad face.
gecko zzed - This is our set-up. Vista laptop, basic version of emagic logic and various instruments.
First we laid down a generic drum track with a digital guitar effects pedal plugged directly into the laptop's mike hole with a lead (note my technical language there). The track was recorded in a new file in emagic logic. I don't really know if that's going directly through the sound card or not.
The second track is guitar played through the same pedal plugged in the same way with the first track playing through the computers speakers to play along to.
When we play back both tracks together, the guitar is slightly behind the first drum track even though it was played correctly and the drum track is also recorded again slightly behind the drums on the first track. The result is drums with an echo and a sloppy guitar track.
We've actually tried this same set-up on three different computers with audacity instead of emagic logic and the result is basically the same so we are clearly idiots.
ez willis - how do I find out if the tracks are set for stereo and how do I change that? I had a look about and can't see a reference to stereo or mono.
Steenamaroo - What's windows mixer? If I go to the sound settings in my control panel the only thing I can see that might make a difference is the sample rate and bit depth etc. This is set to "2 channel, 16 bit, 44100 Hz" to match the setting in emagic logic. Is the 2 channel thing a stereo refence? There are no options to select 1 channel in the drop-down box.
darrin h2000 - If I mute track 2 we won't have any guitar!
My sad face is coming back... 3 computers, 2 software packages, nothing listenable. The sound quality on logic is infinitely better than with audacity. Perhaps this is my punishment for cheaping out.
Sad face revisited, huh?
Okay . . . there are many things to deal with here. If you are plugging directly into the laptop's mike hole (I am also familiar with technological language), then this means that you are using the laptop's inbuilt soundcard. This is likely to be the source of most, if not all, of your recording woes. Most internal cards, though you can use them for recording, are not designed for the sort of recording you are trying to do. If you are keen on pursuing this recording idea, then you should consider investing in a recording interface designed specifically for this purpose. Their are relatively cheap USB interfaces on the makret which will suit your purposes. You will be able to plug instruments or mikes into them. Logic will recognise the USB connection, and you won't experience the delay, and you can avoid the crosstalk (i.e. sound going from one track to the next).
I expect that the three different computers you've tried all have internal soundcards and are all displaying similar problems.
It's possible that tracks being set for stereo might be a problem. But I don't think that's the case in this instance. When you are in Logic, at the bottom of a track on the mixer window, next to the 'Rec' button is either a circle (mono) or two interlocking circles (stereo). You can toggle from one to the other. Above the track fader there is an input button from which you can select the input. I don't know whether the mike hole is built for a stereo or mono input, but Logic tracks default to left (or 1) then right (2). I really don't think this is causing you your problems though.
You should investigate the windows mixer referred to by Steenamaroo. I'm on XP, so I don't know how this works in Vista. However, somewhere you should be able to find a Control Panel, then Sounds and Audio Devices, then an Audio section. Within this, you should be able to pick your default recording device. Here is where you need to make sure that only the mike input has been selected. It is possible that the laptop is recording whatever it 'hears', from no matter what source (including itself, somehow).
Darrin
h2000's suggestion of muting a track has merit, if to do nothing else than confirm that you can get a crosstalk free track. For example, you have your already-recorded drum track. Try muting that, and play guitar (at this stage we don't care if it's in time or not), and see if this results in a guitar without any unwanted rubbish on it.
You should also try recording the guitar without using the laptop's speakers, but using a set of headphones instead (so long as you can feed what you are recording into them as well as what the laptop is playing back for you). Again, this probably requires an exploration of the audio options in the control panel.