Scanning error

My company is currently demo-ing this product, and have liked it so far. However, I'm having problems getting the asset scanning to work. I have confirmed and re-confirmed (and re-confirmed a dozen times) that Remote DCOM is enabled on the client, and set the permissions in dcomcnfg appropriatly, and WMI is installed and enabled. However, I'm still seeing the error: Error : Either access denied for the user or the remote DCOM option might be disabled in the workstation. I am using the Domain scan, and appropriate domain credentials have been supplied. Any assistance would be great!

we're using 7.0.0 Build 7021. Client is Windows XP
server is hosted on 2003 Standard, R2 SP2