Issues with filesharing b/w PC and laptop

Ok, I have a Linksys wireless router that's used for internet only atm.

There are two systems I need to have filesharing between (My PC and my laptop) but only between those two systems. My problem is that no matter how I try to set it up, my laptop refuses to access my PC, I did get it to "see" it but it asks for authorization. The authorization window doesn't work even when you put legit passwords/usernames in it.

My PC can see the notebook just fine, and can even send files to it.

The PC uses Windows XP Pro SP1, the notebook uses Windows XP Home SP2.

Any ideas?