The limits of Dataloader are described in https://na10.salesforce.com/help/pdfs/en/salesforce_data_loader.pdf. The number of records is a limit of the Bulk API which is 5 000 000 records as stated in https://help.salesforce.com/HTViewHelpDoc?id=when_to_use_the_data_loader.htm&language=en_US
The number of records is a limit of the Bulk API which is 5 000 000 records as stated in https://help.salesforce.com/HTViewHelpDoc?id=when_to_use_the_data_loader.htm&language=en_US