Once you've added your user dataclass it should become a table on the Altiris database.  You should then be able to Join that table on the ResourceGuid column (it can go by a couple of names depending on what you're joining) and any fields you've added to that Dataclass will match up as long as the Dataclass has been added to your Resource Type.

I did an article on asset report writing awhile back that might help:
https://www-secure.symantec.com/connect/articles/asset-report-writing-tips

If you need this on all your assets, make sure you link the dataclass to the "Asset" resource type so all resource types will inherit that dataclass.

Thanks to both of you who responded.  Since these are two fields that are need for every asset type I indeed added it to the Asset Resource Type (thanks EMercado).  And MBHarmon that article you wrote looks great.  Going to do some testing today and see how it all goes.  Will let you both know how it goes.

OK..I was able to run a report almost the way I want it.  One other question (and this just came to me from mgmt).  The dataclass I added was a static drop down box with three choices.  They would like a report that allows for a picker to be used to choose between the choices instead of three different reports.  Any article or anything that I can be pointed to do accomplish this.  Hopefully this is the last piece to this small project.

Thanks