You may need to join the forums and elaborate on what exactly you'd like it to do for us to answer better.
If you just want your macbook to be able to connect to your wireless, then just about any router will work for that.
If you want to link your macbook with your PC and share files, then you need to properly configure both of them while they're on the same network, adding devices will not affect that.
If you want to get an external storage device that both your PC and macbook can access over the network that will also be able to replace your existing router, then the Time Capsule is a good choice for that.
It is definitely possible, you just need to configure the Macbook's SMB sharing options, and ensure that the Windows filesharing settings allow the mac in. No extra hardware required. 
Here's a document from Apple's website that gives some info on how to set it up. If you need any help with that feel free to ask, or Futureshop has technicians that can do that in your home, or online even.
