To create an Attachments user defined field:

1. Click Management
2. Click User Defined Fields
3. click Base
4. Click New Defined Field
5. Name it Attachment?
6. For Field Data Type choose Text
7. click Next
8. For Field Application select Calendar Item, Contact, Note, Transaction (you want this field to exist on all journal entries)
9. Click Next
10. For Display Type select 'Selection From a Set of Values'
11. Click Next
12. For Values type Yes and click Add, then type No and click Add
13. Click Save and Finish

Once that is created, the next time you add a journal entry with an attachment, find the Attachment? field in the User Defined Fields area and select 'Yes'.  You can then create a query to find all journal entries that have attachments by following these steps:

1. Click Queries
2. Select a category that you want to store this query in (Ex: Base)
3. Click New Query under the Tasks menu
4. Name the query
5. For Starting Query select Category: Base and Query: All Constituents
6. For the Data Return Type select Journal Entries
7. For Criteria Matching select Match At least one Criteria
8. For Criteria choose UDF: Calendar Item
9. Click Attachments? and choose Yes
10. For Criteria choose UDF: Contact
11. Click Attachments? and choose Yes
12. For Criteria choose UDF: Note
13. Click Attachments? and choose Yes
14. For Criteria choose UDF: Transaction
15. Click Attachments and choose Yes
16. Save and Preview

Note: There is no way to include the actual attachment in these results. It can only provide you with a list of journal entries where you have marked 'yes' for attachments.