I have been working at a conversion script to convert all sf.net bugs to jira bugs. In theory it's possible to convert the sf.net xml dump format to a csv-file that jira can read in; we do have to handle some account name issues etc.
Anyone is welcome to try and convert the data; i have only been trying to convert it using some simple python-based xml reader, and have not been very successful at it :)
JIRA can be used 30 days for free so you can install it locally.
--valhallasw