I think they're watching me...

Alright, so I think my roommates may be monitoring what I do on my laptop.

But, I have no idea how to go about achieving that. They're gone a lot now because they have bitchy GFs that take all their time so I could easily get on their computers. What would I need to check to see if they can monitor what I do on my shitty laptop?

Nonono, I mean, they have their own desktops(yes, there's THREE computers in our apartment), and we all share the same modem(obviously) and I'm just wondering if they can see what I do on mine through some random network connection thing.