Many organisations have long-term maintenance requirements for their digital assets, and it is often the case that those assets outlive the tools that were used to generate them. In many usage scenarios such assets are kept in proprietary file formats, thus increasing the risks for the organisation. In this paper we report from a case study aiming to analyse tool support for data curation and long-term maintenance of documents in standardised XML-based document formats. Our investigation includes analysis of both Open Source and proprietary tools using a rich resource of corporate documents initially created in a proprietary document format. Specifically, we investigate a number of tools implementing ODF and OfficeOpen XML in order to establish their support for data curation and long-term maintenance of documents. We found that support for data curation by migration from the investigated proprietary document format to the two standardised XML-based document formats do not satisfy the organisation’s expectations. Our study reports on a range of problems associated with the use of proprietary file formats and provides a basis for strategic consideration of these issues.