I was working with a client who was trying to get data imported into Salesforce.com from the Professional edition. They were hoping to be able to use the Apex Data Loader. They were surprised to learn that the data loader cannot be used by Professional Edition. That version doesn't have API access and that access is required for the Apex Data Loader.
So what do you do? The Salesforce.com Excel Connector. There might be other free ways to import data into Professional Edition, but if so, I haven't found them. The Excel Connector works great, but it is a serious challenge for the uninitiated to get figured out. I have frequently told clients where to find the excel connector, but they usually need a little assistance getting it installed properly and figuring out how to use it.
There are a couple things I really like about the Excel Connector for Salesforce. One is that it lets you import or update records to any object in Salesforce, even in Professional Edition. It is much more powerful than the import wizards provided by Salesforce. But even better than that, when you do insert a new record, the Excel Connector for Salesforce returns into the excel file the ID of the records you just inserted. Even the Apex Data Loader doesn't do that. And for that reason, I frequently use the Excel Connector rather than the Apex Data Loader.
Its main serious short coming is that it isn't available for the mac. For a long time it wasn't supported in Vista or Excel 2007, but I think that is resolved now.
Anyway, the Excel Connector for Salesforce.com is an awesome, free way to get any data you need imported, deleted, or updated.
If you need help with any kind of import work, in any edition of Salesforce for any kind of data, feel free to contact us through our website: www.snapptraffic.com. We'd be glad to help.