Knowing that I am an idiot, proceed onward.
Make sure you're connected via ethernet or wireless with a router or switch. I can't help you with a "direct connection" because I'm not smhhat enuf.
PC SIDE:::
You should have file sharing turned on on the PC, or at least enable file sharing on a folder. Stand by .... Booting parallels to be sure I'm not talking out of my @$$...
Right click on whatever folder on the PC you wish to share the contents from and go to properties-
Select the "sharing" tab.
Under "Network sharing and security" click the "if you understand the risks and want to blah blah blah" sentence.
Now the pop up select "Just enable file sharing". and click ok.
Now the box will be open on the first screen "share this folder on the network" check it off.
Make a share name for this folder that you will be able to find easily and hit ok or apply.
Now, good idea to reboot the PC to be sure all the changes took effect. While you're waiting, good idea to reboot the MAC to make sure it refreshes too -- this is more out of voodoo.
MAC Side:::
Go to Macintosh HD and select network (after the PC is good and booted up) wait a minute before clicking, it can take a moment for the network screen to update.
See if shes there (the PC folder you named) or the PC name. If not, try searching for the folder you just named.
If so, click on it, and the authentication screen should pop up, do NOT put in a password unless youve specified this on the PC. Next select whatever folder / volume you created and click "ok".
It should mount the folder or drive on your desktop, and you can grab files from it. If you want to write TO the PC, you will have to enable write-control on the PC side -- by default, this is read only.
If you're still having some troubles,
Temporarily disable the firewall on the PC, and make sure the firewall settings on the MAC are not going to conflict -- On the Mac go to System pref, internet and network, sharing, verify that "Personal File Sharing" is enabled on the services tab, and on the firewall tab too.
Best of luck to you.