Trying to Share Files from Mac to PC

I can see and share Mac files from my PC but can't seem connect to the PC from my Mac. I did have this working in both directions at some point.

Here's what I've done to try and troubleshoot this issue.

The PC and Mac are connected to the router by ethernet cable.
I've verified that the PC's IP address is correct, by running ipconfig on PC the side.
I've disabled Windows Filewall and I manually turn off ZoneAlarm.
In Finder, I select "Go", "Connect to Server".
I enter smb:// 192.168.1.30 in Server Address, click "Connect"
In the "Enter your name and password for the server...", I Connect as a Registered Guest, the name field is filled in (with my name), password is blank.

After entering my password, I get "You entered and invalid username or password"
The user name and passwords are the same for both machines.
On the PC it's the only user and I'm an admin.
Running Win XP, SP 3; OS X 10.6

I don't know what else it could be...Any suggestions are appreciated!

Hi Abbie,

Welcome to the Mac Forums! Great to have a new user on board

Just wanted to verify with you -
When I connect using the SMB I don't connect as Registered Guest, I leave that unchecked and use my PC's username and password to log in. Did you try that way? I accidently had that registered guest thing on and it wouldn't accept it. If you uncheck it and use the XP machine username and password you should be able to log in that way.

Let me know how you go!

Thanks for your suggestion ShadowDan. I'm actually using "Registered User" NOT "Registered Guest". (My mistake, Sorry). Then I enter my PC's username and password.

I noticed that in the upper area of left the Finder window, there's the name of the my XP host, AbbiesComputer. When i click it, I get "Connection failed". I think it's an older entry and may not point to a valid ip address.

How to I find out what address that name is mapped to?

Thanks.