Though I'm new here...I'd have to agree with Sandi...
Here's an idea - I guess she probably wouldn't give you access to her laptop at least on a routine basis. Depending how technical you are --- You have a few options:
1) Look around...get a commercial or open source key logger that you can completely hide in the background. Try to get it installed one day on hers and then you can map into her PC remotely from yours (if you know any acct on here) to analyze the logs.
2) Since she's carrying it with her i'm assuming it's wireless - get a packet sniffer installed on YOUR machine - you can then grab all wireless packets coming across your router to analyze. Some packet sniffers are already setup out of the box to grab all the standard chat conversations - MSN, AIM, etc.
